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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1606.09430
|
Georgios Lukes Gerakopoulos
|
Georgios Lukes-Gerakopoulos
|
Spinning particles moving around black holes: integrability and chaos
|
6 pages, 2 figures, to appear in the Proceedings of the "14th Marcel
Grossmann Meeting" (Rome, July 12 - 18, 2015)
| null |
10.1142/9789813226609_0209
| null |
gr-qc nlin.CD
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The motion of a stellar compact object around a supermassive black hole can
be approximated by the motion of a spinning test particle. The equations of
motion describing such systems are in general non-integrable, and therefore,
chaotic motion should be expected. This article discusses the integrability
issue of the spinning particle for the cases of Schwarzschild and Kerr
spacetime, and then it focuses on a canonical Hamiltonian formalism where the
spin of the particle is included only up to the linear order.
|
[
{
"created": "Thu, 30 Jun 2016 11:05:02 GMT",
"version": "v1"
}
] |
2019-03-06
|
[
[
"Lukes-Gerakopoulos",
"Georgios",
""
]
] |
The motion of a stellar compact object around a supermassive black hole can be approximated by the motion of a spinning test particle. The equations of motion describing such systems are in general non-integrable, and therefore, chaotic motion should be expected. This article discusses the integrability issue of the spinning particle for the cases of Schwarzschild and Kerr spacetime, and then it focuses on a canonical Hamiltonian formalism where the spin of the particle is included only up to the linear order.
|
0906.5067
|
Ahmadjon Abdujabbarov
|
A.I. Mamadjanov, A.A. Hakimov, S.R. Tojiev
|
Quantum Interference Effects in Spacetime of Slowly Rotating Compact
Objects in Braneworld
|
12 pages, 2 figures
|
Mod.Phys.Lett.A25:243-256,2010
|
10.1142/S0217732310032482
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The phase shift a neutron interferometer caused by the gravitational field
and the rotation of the earth is derived in a unified way from the standpoint
of general relativity. General relativistic quantum interference effects in the
slowly rotating braneworld as the Sagnac effect and phase shift effect of
interfering particle in neutron interferometer are considered. It was found
that in the case of the Sagnac effect the influence of brane parameter is
becoming important due to the fact that the angular velocity of the locally non
rotating observer must be larger than one in the Kerr space-time. In the case
of neutron interferometry it is found that due to the presence of the parameter
$Q^{*}$ an additional term in the phase shift of interfering particle emerges
from the results of the recent experiments we have obtained upper limit for the
tidal charge as $Q^{*}\lesssim 10^{7} \rm{cm}^{2}$. Finally, as an example, we
apply the obtained results to the calculation of the (ultra-cold neutrons)
energy level modification in the braneworld.
|
[
{
"created": "Sat, 27 Jun 2009 11:05:13 GMT",
"version": "v1"
}
] |
2010-03-02
|
[
[
"Mamadjanov",
"A. I.",
""
],
[
"Hakimov",
"A. A.",
""
],
[
"Tojiev",
"S. R.",
""
]
] |
The phase shift a neutron interferometer caused by the gravitational field and the rotation of the earth is derived in a unified way from the standpoint of general relativity. General relativistic quantum interference effects in the slowly rotating braneworld as the Sagnac effect and phase shift effect of interfering particle in neutron interferometer are considered. It was found that in the case of the Sagnac effect the influence of brane parameter is becoming important due to the fact that the angular velocity of the locally non rotating observer must be larger than one in the Kerr space-time. In the case of neutron interferometry it is found that due to the presence of the parameter $Q^{*}$ an additional term in the phase shift of interfering particle emerges from the results of the recent experiments we have obtained upper limit for the tidal charge as $Q^{*}\lesssim 10^{7} \rm{cm}^{2}$. Finally, as an example, we apply the obtained results to the calculation of the (ultra-cold neutrons) energy level modification in the braneworld.
|
gr-qc/0312119
|
Miguel Lorente
|
M. Lorente
|
Quantum process and the foundation of relational theories of space-time
|
Proceedings: J. Diaz Alonso, M. Lorente eds. (Frontieres, Paris 1994)
pp. 297-302. LaTeX, 6 pages, 1 eps figure (late submission)
| null | null | null |
gr-qc
| null |
We present current theories about the structure of space and time, where the
building blocks are some fundamental entities (yes-no experiment, quantum
processes, spin net-work, preparticles) that do not presuppose the existence of
space and time. The relations among these objects are the base for a
pregeometry of discrete character, the continuous limit of which gives rise to
the physical properties of the space and time.
|
[
{
"created": "Tue, 30 Dec 2003 11:10:35 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Lorente",
"M.",
""
]
] |
We present current theories about the structure of space and time, where the building blocks are some fundamental entities (yes-no experiment, quantum processes, spin net-work, preparticles) that do not presuppose the existence of space and time. The relations among these objects are the base for a pregeometry of discrete character, the continuous limit of which gives rise to the physical properties of the space and time.
|
2211.01807
|
Muhammad Sharif
|
M. Sharif and Komal Hassan
|
Influence of Charge on Decoupled Anisotropic Spheres in $f(G,T)$ Gravity
|
33 pages, 10 figures
|
Eur. Phys. J. Plus 137(2022)997
| null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we develop two anisotropic solutions for static
self-gravitating spherical structure in the presence of electromagnetic field
through gravitational decoupling approach in $f(G,T)$ theory, where $G$ and $T$
denote the Gauss-Bonnet term and trace of the energy-momentum tensor,
respectively. The extra source with isotropic seed sector is responsible for
generating anisotropy in the spacetime. The system of field equations is
decoupled into two arrays by using minimal geometric deformation in the radial
component. The first set portrays the isotropic regime whereas the second set
represents the anisotropic system. The metric coefficients of the Krori-Barua
spacetime are employed to extract solution of the first set while two
constraints on the radial and temporal components of the extra source yield the
corresponding two solutions. Finally, we investigate the influence of charge
and decoupling parameter on the physical viability and stability of the
obtained solutions. We conclude that the resulting solutions in this modified
theory indicate more feasible and stable structures.
|
[
{
"created": "Wed, 2 Nov 2022 02:47:24 GMT",
"version": "v1"
}
] |
2022-11-04
|
[
[
"Sharif",
"M.",
""
],
[
"Hassan",
"Komal",
""
]
] |
In this paper, we develop two anisotropic solutions for static self-gravitating spherical structure in the presence of electromagnetic field through gravitational decoupling approach in $f(G,T)$ theory, where $G$ and $T$ denote the Gauss-Bonnet term and trace of the energy-momentum tensor, respectively. The extra source with isotropic seed sector is responsible for generating anisotropy in the spacetime. The system of field equations is decoupled into two arrays by using minimal geometric deformation in the radial component. The first set portrays the isotropic regime whereas the second set represents the anisotropic system. The metric coefficients of the Krori-Barua spacetime are employed to extract solution of the first set while two constraints on the radial and temporal components of the extra source yield the corresponding two solutions. Finally, we investigate the influence of charge and decoupling parameter on the physical viability and stability of the obtained solutions. We conclude that the resulting solutions in this modified theory indicate more feasible and stable structures.
|
1012.3173
|
Ulrich Sperhake
|
Ulrich Sperhake, Bernd Bruegmann, Doreen Mueller, Carlos F. Sopuerta
|
Black-hole binaries go to eleven orbits
|
Matches version to be published in CQG, 16 pages, 8 figures
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We analyse an eleven-orbit inspiral of a non-spinning black-hole binary with
mass ratio q=M1/M2=4. The numerically obtained gravitational waveforms are
compared with post-Newtonian (PN) predictions including several sub-dominant
multipoles up to multipolar indices (l=5,m=5). We find that (i) numerical and
post-Newtonian predictions of the phase of the (2,2) mode accumulate a phase
difference of about 0.35 rad at the PN cut off frequency 0.1 for the Taylor T1
approximant when numerical and PN waveforms are matched over a window in the
early inspiral phase; (ii) in contrast to previous studies of equal-mass and
specific spinning binaries, we find the Taylor T4 approximant to agree less
well with numerical results, provided the latter are extrapolated to infinite
extraction radius; (iii) extrapolation of gravitational waveforms to infinite
extraction radius is particularly important for subdominant multipoles with l
unequal m; (iv) 3PN terms in post-Newtonian multipole expansions significantly
improve the agreement with numerical predictions for sub-dominant multipoles.
|
[
{
"created": "Tue, 14 Dec 2010 21:05:18 GMT",
"version": "v1"
},
{
"created": "Tue, 7 Jun 2011 11:53:07 GMT",
"version": "v2"
}
] |
2011-06-08
|
[
[
"Sperhake",
"Ulrich",
""
],
[
"Bruegmann",
"Bernd",
""
],
[
"Mueller",
"Doreen",
""
],
[
"Sopuerta",
"Carlos F.",
""
]
] |
We analyse an eleven-orbit inspiral of a non-spinning black-hole binary with mass ratio q=M1/M2=4. The numerically obtained gravitational waveforms are compared with post-Newtonian (PN) predictions including several sub-dominant multipoles up to multipolar indices (l=5,m=5). We find that (i) numerical and post-Newtonian predictions of the phase of the (2,2) mode accumulate a phase difference of about 0.35 rad at the PN cut off frequency 0.1 for the Taylor T1 approximant when numerical and PN waveforms are matched over a window in the early inspiral phase; (ii) in contrast to previous studies of equal-mass and specific spinning binaries, we find the Taylor T4 approximant to agree less well with numerical results, provided the latter are extrapolated to infinite extraction radius; (iii) extrapolation of gravitational waveforms to infinite extraction radius is particularly important for subdominant multipoles with l unequal m; (iv) 3PN terms in post-Newtonian multipole expansions significantly improve the agreement with numerical predictions for sub-dominant multipoles.
|
0901.0278
|
Gon\c{c}alo Dias
|
Gon\c{c}alo A. S. Dias and Jos\'e P. S. Lemos
|
Hamiltonian thermodynamics of d-dimensional (d=4 and d>4)
Reissner-Nordstr\"om anti-de Sitter black holes with spherical, planar, and
hyperbolic topology
|
24 pages, 3 figures, published version
|
Phys.Rev.D79:044013,2009
|
10.1103/PhysRevD.79.044013
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The Hamiltonian thermodynamics formalism is applied to the general
$d$-dimensional Reissner-Nordstr\"om-anti-de Sitter black hole with spherical,
planar, and hyperbolic horizon topology. After writing its action and
performing a Legendre transformation, surface terms are added in order to
guarantee a well defined variational principle with which to obtain sensible
equations of motion, and also to allow later on the thermodynamical analysis.
Then a Kucha\v{r} canonical transformation is done, which changes from the
metric canonical coordinates to the physical parameters coordinates. Again a
well defined variational principle is guaranteed through boundary terms. These
terms influence the fall-off conditions of the variables and at the same time
the form of the new Lagrange multipliers. Reduction to the true degrees of
freedom is performed, which are the conserved mass and charge of the black
hole. Upon quantization a Lorentzian partition function $Z$ is written for the
grand canonical ensemble, where the temperature $\bf T$ and the electric
potential $\phi$ are fixed at infinity. After imposing Euclidean boundary
conditions on the partition function, the respective effective action $I_*$,
and thus the thermodynamical partition function, is determined for any
dimension $d$ and topology $k$. This is a quite general action. Several
previous results can be then condensed in our single general formula for the
effective action $I_*$. Phase transitions are studied for the spherical case,
and it is shown that all the other topologies have no phase transitions. A
parallel with the Bose-Einstein condensation can be established. Finally, the
expected values of energy, charge, and entropy are determined for the black
hole solution.
|
[
{
"created": "Fri, 2 Jan 2009 20:36:39 GMT",
"version": "v1"
},
{
"created": "Tue, 6 Jan 2009 22:19:00 GMT",
"version": "v2"
},
{
"created": "Sat, 23 May 2009 20:29:11 GMT",
"version": "v3"
}
] |
2009-11-13
|
[
[
"Dias",
"Gonçalo A. S.",
""
],
[
"Lemos",
"José P. S.",
""
]
] |
The Hamiltonian thermodynamics formalism is applied to the general $d$-dimensional Reissner-Nordstr\"om-anti-de Sitter black hole with spherical, planar, and hyperbolic horizon topology. After writing its action and performing a Legendre transformation, surface terms are added in order to guarantee a well defined variational principle with which to obtain sensible equations of motion, and also to allow later on the thermodynamical analysis. Then a Kucha\v{r} canonical transformation is done, which changes from the metric canonical coordinates to the physical parameters coordinates. Again a well defined variational principle is guaranteed through boundary terms. These terms influence the fall-off conditions of the variables and at the same time the form of the new Lagrange multipliers. Reduction to the true degrees of freedom is performed, which are the conserved mass and charge of the black hole. Upon quantization a Lorentzian partition function $Z$ is written for the grand canonical ensemble, where the temperature $\bf T$ and the electric potential $\phi$ are fixed at infinity. After imposing Euclidean boundary conditions on the partition function, the respective effective action $I_*$, and thus the thermodynamical partition function, is determined for any dimension $d$ and topology $k$. This is a quite general action. Several previous results can be then condensed in our single general formula for the effective action $I_*$. Phase transitions are studied for the spherical case, and it is shown that all the other topologies have no phase transitions. A parallel with the Bose-Einstein condensation can be established. Finally, the expected values of energy, charge, and entropy are determined for the black hole solution.
|
0710.0999
|
Julio Cesar Fabris
|
A.B. Batista, J.C. Fabris, M. J. S. Houndjo
|
Particle Production in an expanding universe dominated by dark energy
fluid
|
Latex file, 14 pages, 1 figure in EPS format
|
Grav.Cosmol.14:140-146,2008
|
10.1134/S0202289308020035
| null |
gr-qc astro-ph hep-th
| null |
We investigate the fate of particle production in an expanding universe
dominated by a perfect fluid with equation of state $p = \alpha\rho$. The rate
of particle production, using the Bogolioubov coefficients, are determined
exactly for any value of $\alpha$ in the case of a flat universe. When the
strong energy condition is satisfied, the rate of particle production decreases
as time goes on, in agreement to the fact that the four-dimensional curvature
decreases with the expansion; the opposite occurs when the strong energy
condition is violated. In the phantomic case, the rate of particle production
diverges in a finite time. This may lead to a backreaction effect, leading to
the avoidance of the big rip singularity, specially if $- 1 > \alpha > -
{5/3}$.
|
[
{
"created": "Thu, 4 Oct 2007 12:49:14 GMT",
"version": "v1"
}
] |
2012-07-06
|
[
[
"Batista",
"A. B.",
""
],
[
"Fabris",
"J. C.",
""
],
[
"Houndjo",
"M. J. S.",
""
]
] |
We investigate the fate of particle production in an expanding universe dominated by a perfect fluid with equation of state $p = \alpha\rho$. The rate of particle production, using the Bogolioubov coefficients, are determined exactly for any value of $\alpha$ in the case of a flat universe. When the strong energy condition is satisfied, the rate of particle production decreases as time goes on, in agreement to the fact that the four-dimensional curvature decreases with the expansion; the opposite occurs when the strong energy condition is violated. In the phantomic case, the rate of particle production diverges in a finite time. This may lead to a backreaction effect, leading to the avoidance of the big rip singularity, specially if $- 1 > \alpha > - {5/3}$.
|
gr-qc/9801009
|
Eugenio Mello
|
E. R. Bezerra de Mello, V. B. Bezerra and Yu. V. Grats
|
Self-forces in the Spacetime of Multiple Cosmic Strings
|
This paper has been produced in Latex format and has 18 pages
|
Class.Quant.Grav. 15 (1998) 1915-1925
|
10.1088/0264-9381/15/7/009
| null |
gr-qc
| null |
We calculate the electromagnetic self-force on a stationary linear
distribution of four-current in the spacetime of multiple cosmic strings. It is
shown that if the current is infinitely thin and stretched along a line which
is parallel to the strings the problem admits an explicit solution.
|
[
{
"created": "Tue, 6 Jan 1998 11:32:19 GMT",
"version": "v1"
}
] |
2009-10-31
|
[
[
"de Mello",
"E. R. Bezerra",
""
],
[
"Bezerra",
"V. B.",
""
],
[
"Grats",
"Yu. V.",
""
]
] |
We calculate the electromagnetic self-force on a stationary linear distribution of four-current in the spacetime of multiple cosmic strings. It is shown that if the current is infinitely thin and stretched along a line which is parallel to the strings the problem admits an explicit solution.
|
1811.11912
|
Fabio Novaes
|
F\'abio Novaes, C\'assio Marinho, M\'at\'e Lencs\'es and Marc Casals
|
Kerr-de Sitter Quasinormal Modes via Accessory Parameter Expansion
|
38+19 pages, 8 figures. v3: minor changes, matches published version
|
JHEP 1905 (2019) 033
|
10.1007/JHEP05(2019)033
| null |
gr-qc hep-th math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Quasinormal modes are characteristic oscillatory modes that control the
relaxation of a perturbed physical system back to its equilibrium state. In
this work, we calculate QNM frequencies and angular eigenvalues of Kerr--de
Sitter black holes using a novel method based on conformal field theory. The
spin-field perturbation equations of this background spacetime essentially
reduce to two Heun's equations, one for the radial part and one for the angular
part. We use the accessory parameter expansion of Heun's equation, obtained via
the isomonodromic $\tau$-function, in order to find analytic expansions for the
QNM frequencies and angular eigenvalues. The expansion for the frequencies is
given as a double series in the rotation parameter $a$ and the extremality
parameter $\epsilon=(r_{C}-r_{+})/L$, where $L$ is the de Sitter radius and
$r_{C}$ and $r_{+}$ are the radii of, respectively, the cosmological and event
horizons. Specifically, we give the frequency expansion up to order
$\epsilon^2$ for general $a$, and up to order $\epsilon^{3}$ with the
coefficients expanded up to $(a/L)^{3}$. Similarly, the expansion for the
angular eigenvalues is given as a series up to $(a\omega)^{3}$ with
coefficients expanded for small $a/L$. We verify the new expansion for the
frequencies via a numerical analysis and that the expansion for the angular
eigenvalues agrees with results in the literature.
|
[
{
"created": "Thu, 29 Nov 2018 01:45:52 GMT",
"version": "v1"
},
{
"created": "Wed, 6 Feb 2019 18:20:08 GMT",
"version": "v2"
},
{
"created": "Thu, 9 May 2019 00:30:49 GMT",
"version": "v3"
}
] |
2019-05-10
|
[
[
"Novaes",
"Fábio",
""
],
[
"Marinho",
"Cássio",
""
],
[
"Lencsés",
"Máté",
""
],
[
"Casals",
"Marc",
""
]
] |
Quasinormal modes are characteristic oscillatory modes that control the relaxation of a perturbed physical system back to its equilibrium state. In this work, we calculate QNM frequencies and angular eigenvalues of Kerr--de Sitter black holes using a novel method based on conformal field theory. The spin-field perturbation equations of this background spacetime essentially reduce to two Heun's equations, one for the radial part and one for the angular part. We use the accessory parameter expansion of Heun's equation, obtained via the isomonodromic $\tau$-function, in order to find analytic expansions for the QNM frequencies and angular eigenvalues. The expansion for the frequencies is given as a double series in the rotation parameter $a$ and the extremality parameter $\epsilon=(r_{C}-r_{+})/L$, where $L$ is the de Sitter radius and $r_{C}$ and $r_{+}$ are the radii of, respectively, the cosmological and event horizons. Specifically, we give the frequency expansion up to order $\epsilon^2$ for general $a$, and up to order $\epsilon^{3}$ with the coefficients expanded up to $(a/L)^{3}$. Similarly, the expansion for the angular eigenvalues is given as a series up to $(a\omega)^{3}$ with coefficients expanded for small $a/L$. We verify the new expansion for the frequencies via a numerical analysis and that the expansion for the angular eigenvalues agrees with results in the literature.
|
1003.3491
|
Leonardo Castaneda
|
Diego Caceres, Leonardo Castaneda, Juan M. Tejeiro
|
Shear Dynamics in Bianchi I Cosmology
|
10 pages, 6 figures, Comments and suggestions are welcome.
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present the exact equation for evolution of Bianchi I cosmological model,
considering a non-tilted perfect fluid in a matter dominated universe. We use
the definition of shear tensor and later we prove it is consistent with the
evolution equation for shear tensor obtained from Ricci identities and widely
known in literature [3], [5], [9]. Our result is compared with the equation
given by Ellis and van Elst in [3] and Tsagas, Challinor and Maartens [5]. We
consider that it is important to clarify the notation used in [3], [5] related
with the covariant derivative and the behavior of the shear tensor.
|
[
{
"created": "Wed, 17 Mar 2010 23:06:01 GMT",
"version": "v1"
}
] |
2010-03-19
|
[
[
"Caceres",
"Diego",
""
],
[
"Castaneda",
"Leonardo",
""
],
[
"Tejeiro",
"Juan M.",
""
]
] |
We present the exact equation for evolution of Bianchi I cosmological model, considering a non-tilted perfect fluid in a matter dominated universe. We use the definition of shear tensor and later we prove it is consistent with the evolution equation for shear tensor obtained from Ricci identities and widely known in literature [3], [5], [9]. Our result is compared with the equation given by Ellis and van Elst in [3] and Tsagas, Challinor and Maartens [5]. We consider that it is important to clarify the notation used in [3], [5] related with the covariant derivative and the behavior of the shear tensor.
|
1504.04079
|
Grigorios Fournodavlos
|
Grigorios Fournodavlos
|
On the backward stability of the Schwarzschild black hole singularity
|
6 Figures
| null |
10.1007/s00220-016-2681-0
| null |
gr-qc math.AP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the backwards-in-time stability of the Schwarzschild singularity
from a dynamical PDE point of view. More precisely, considering a spacelike
hypersurface $\Sigma_0$ in the interior of the black hole region, tangent to
the singular hypersurface $\{r=0\}$ at a single sphere, we study the problem of
perturbing the Schwarzschild data on $\Sigma_0$ and solving the Einstein vacuum
equations backwards in time. We obtain a local well-posedness result for small
perturbations lying in certain weighted Sobolev spaces. No symmetry assumptions
are imposed. The perturbed spacetimes all have a singularity at a "collapsed"
sphere on $\Sigma_0$, where the leading asymptotics of the curvature and the
metric match those of their Schwarzschild counterparts to a suitably high
order. As in the Schwarzschild backward evolution, the pinched initial
hypersurface $\Sigma_0$ `opens up' instantly, becoming a smooth spacelike
(cylindrical) hypersurface. This result thus yields classes of examples of
non-symmetric vacuum spacetimes, evolving forward-in-time from smooth initial
data, which form a Schwarzschild type singularity at a collapsed sphere. We
rely on a precise asymptotic analysis of the Schwarzschild geometry near the
singularity which turns out to be at the threshold that our energy methods can
handle.
|
[
{
"created": "Thu, 16 Apr 2015 01:32:38 GMT",
"version": "v1"
}
] |
2016-07-20
|
[
[
"Fournodavlos",
"Grigorios",
""
]
] |
We study the backwards-in-time stability of the Schwarzschild singularity from a dynamical PDE point of view. More precisely, considering a spacelike hypersurface $\Sigma_0$ in the interior of the black hole region, tangent to the singular hypersurface $\{r=0\}$ at a single sphere, we study the problem of perturbing the Schwarzschild data on $\Sigma_0$ and solving the Einstein vacuum equations backwards in time. We obtain a local well-posedness result for small perturbations lying in certain weighted Sobolev spaces. No symmetry assumptions are imposed. The perturbed spacetimes all have a singularity at a "collapsed" sphere on $\Sigma_0$, where the leading asymptotics of the curvature and the metric match those of their Schwarzschild counterparts to a suitably high order. As in the Schwarzschild backward evolution, the pinched initial hypersurface $\Sigma_0$ `opens up' instantly, becoming a smooth spacelike (cylindrical) hypersurface. This result thus yields classes of examples of non-symmetric vacuum spacetimes, evolving forward-in-time from smooth initial data, which form a Schwarzschild type singularity at a collapsed sphere. We rely on a precise asymptotic analysis of the Schwarzschild geometry near the singularity which turns out to be at the threshold that our energy methods can handle.
|
1108.5561
|
Paul Romatschke
|
Paul Romatschke
|
Relativistic (Lattice) Boltzmann Equation with Non-Ideal Equation of
State
|
19 pages, 4 figures; v2: new section IVB on shear and bulk
viscosities & changes reflecting referee's comments
| null |
10.1103/PhysRevD.85.065012
| null |
gr-qc hep-th nucl-th physics.flu-dyn
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The relativistic Boltzmann equation for a single particle species generally
implies a fixed, unchangeable equation of state that corresponds to that of an
ideal gas. Real-world systems typically have more complicated equation of state
which cannot be described by the Boltzmann equation. The present work derives a
'Boltzmann-like' equation that gives rise to a conserved energy-momentum tensor
with an arbitrary (but thermodynamically consistent) equation of state. Using
this, a Lattice Boltzmann scheme for diagonal metric tensors and arbitrary
equations of state is constructed. The scheme is verified for QCD in the Milne
metric by comparing to viscous fluid dynamics.
|
[
{
"created": "Mon, 29 Aug 2011 14:21:55 GMT",
"version": "v1"
},
{
"created": "Fri, 24 Feb 2012 00:23:00 GMT",
"version": "v2"
}
] |
2013-05-30
|
[
[
"Romatschke",
"Paul",
""
]
] |
The relativistic Boltzmann equation for a single particle species generally implies a fixed, unchangeable equation of state that corresponds to that of an ideal gas. Real-world systems typically have more complicated equation of state which cannot be described by the Boltzmann equation. The present work derives a 'Boltzmann-like' equation that gives rise to a conserved energy-momentum tensor with an arbitrary (but thermodynamically consistent) equation of state. Using this, a Lattice Boltzmann scheme for diagonal metric tensors and arbitrary equations of state is constructed. The scheme is verified for QCD in the Milne metric by comparing to viscous fluid dynamics.
|
gr-qc/0004022
|
Elizabeth Winstanley
|
Adrian C. Ottewill (University College Dublin) and Elizabeth
Winstanley (Oxford University)
|
The renormalized stress tensor in Kerr space-time: general results
|
24 pages, no figures, revtex, minor changes to conclusions
|
Phys.Rev. D62 (2000) 084018
|
10.1103/PhysRevD.62.084018
|
OUTP-99-53P
|
gr-qc
| null |
We derive constraints on the form of the renormalized stress tensor for
states on Kerr space-time based on general physical principles: symmetry, the
conservation equations, the trace anomaly and regularity on (sections of) the
event horizon. This is then applied to the physical vacua of interest. We
introduce the concept of past and future Boulware vacua and discuss the
non-existence of a state empty at both scri- and scri+. By calculating the
stress tensor for the Unruh vacuum at the event horizon and at infinity, we are
able to check our earlier conditions. We also discuss the difficulties of
defining a state equivalent to the Hartle-Hawking vacuum and comment on the
properties of two candidates for this state.
|
[
{
"created": "Fri, 7 Apr 2000 15:27:32 GMT",
"version": "v1"
},
{
"created": "Tue, 20 Jun 2000 15:28:48 GMT",
"version": "v2"
}
] |
2009-10-31
|
[
[
"Ottewill",
"Adrian C.",
"",
"University College Dublin"
],
[
"Winstanley",
"Elizabeth",
"",
"Oxford University"
]
] |
We derive constraints on the form of the renormalized stress tensor for states on Kerr space-time based on general physical principles: symmetry, the conservation equations, the trace anomaly and regularity on (sections of) the event horizon. This is then applied to the physical vacua of interest. We introduce the concept of past and future Boulware vacua and discuss the non-existence of a state empty at both scri- and scri+. By calculating the stress tensor for the Unruh vacuum at the event horizon and at infinity, we are able to check our earlier conditions. We also discuss the difficulties of defining a state equivalent to the Hartle-Hawking vacuum and comment on the properties of two candidates for this state.
|
gr-qc/0112060
|
Petr Hajicek
|
P. Hajicek and I. Kouletsis (University of Berne)
|
Pair of null gravitating shells I. Space of solutions and its symmetries
|
28 pages, 9 figure included in the text, Latex file using amstex,
epic and graphic
|
Class.Quant.Grav. 19 (2002) 2529-2550
|
10.1088/0264-9381/19/10/302
|
BUTP-01/24
|
gr-qc
| null |
The dynamical system constituted by two spherically symmetric thin shells and
their own gravitational field is studied. The shells can be distinguished from
each other, and they can intersect. At each intersection, they exchange energy
on the Dray, 't Hooft and Redmount formula. There are bound states: if the
shells intersect, one, or both, external shells can be bound in the field of
internal shells. The space of all solutions to classical dynamical equations
has six components; each has the trivial topology but a non trivial boundary.
Points within each component are labeled by four parameters. Three of the
parameters determine the geometry of the corresponding solution spacetime and
shell trajectories and the fourth describes the position of the system with
respect to an observer frame. An account of symmetries associated with
spacetime diffeomorphisms is given. The group is generated by an infinitesimal
time shift, an infinitesimal dilatation and a time reversal.
|
[
{
"created": "Sat, 22 Dec 2001 10:51:08 GMT",
"version": "v1"
}
] |
2009-11-07
|
[
[
"Hajicek",
"P.",
"",
"University of Berne"
],
[
"Kouletsis",
"I.",
"",
"University of Berne"
]
] |
The dynamical system constituted by two spherically symmetric thin shells and their own gravitational field is studied. The shells can be distinguished from each other, and they can intersect. At each intersection, they exchange energy on the Dray, 't Hooft and Redmount formula. There are bound states: if the shells intersect, one, or both, external shells can be bound in the field of internal shells. The space of all solutions to classical dynamical equations has six components; each has the trivial topology but a non trivial boundary. Points within each component are labeled by four parameters. Three of the parameters determine the geometry of the corresponding solution spacetime and shell trajectories and the fourth describes the position of the system with respect to an observer frame. An account of symmetries associated with spacetime diffeomorphisms is given. The group is generated by an infinitesimal time shift, an infinitesimal dilatation and a time reversal.
|
2003.05139
|
Semin Xavier
|
Semin Xavier, Jose Mathew and S. Shankaranarayanan
|
Infinitely degenerate exact Ricci-flat solutions in f(R) gravity
|
v2: 15 pages, 1 figure, changed title, added an appendix, accepted in
Classical and Quantum Gravity
| null |
10.1088/1361-6382/abbd0f
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We obtain an infinite number of exact static, Ricci-flat spherically
symmetric vacuum solutions for a class of f(R) theories of gravity. We
analytically derive two exact vacuum black-hole solutions for the same class of
f(R) theories. The two black-hole solutions have the event-horizon at the same
point; however, their asymptotic features are different. Our results suggest
that no-hair theorem may not hold for generic modified gravity theories. We
discuss the implications of our work to distinguish modified gravity theories
from general relativity in gravitational wave detections.
|
[
{
"created": "Wed, 11 Mar 2020 07:22:48 GMT",
"version": "v1"
},
{
"created": "Wed, 30 Sep 2020 16:15:11 GMT",
"version": "v2"
}
] |
2020-10-02
|
[
[
"Xavier",
"Semin",
""
],
[
"Mathew",
"Jose",
""
],
[
"Shankaranarayanan",
"S.",
""
]
] |
We obtain an infinite number of exact static, Ricci-flat spherically symmetric vacuum solutions for a class of f(R) theories of gravity. We analytically derive two exact vacuum black-hole solutions for the same class of f(R) theories. The two black-hole solutions have the event-horizon at the same point; however, their asymptotic features are different. Our results suggest that no-hair theorem may not hold for generic modified gravity theories. We discuss the implications of our work to distinguish modified gravity theories from general relativity in gravitational wave detections.
|
2308.16044
|
Maria Petronikolou
|
Maria Petronikolou, Emmanuel N. Saridakis
|
Alleviating $H_0$ tension in scalar-tensor and bi-scalar-tensor theories
|
20 pages, 4 figures, Invited Contribution to Universe Special Issue
"Modified Gravity Approaches to the Tensions of LambdaCDM", with Editors
Eleonora Di Valentino, Leandros Perivolaropoulos, Jackson Levi Said
|
Universe 2023, 9(9), 397;
|
10.3390/universe9090397
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We investigate scalar-tensor and bi-scalar-tensor modified theories of
gravity that can alleviate the $H_0$ tension. In the first class of theories we
show that choosing particular models with shift-symmetric friction term we are
able to alleviate the tension by obtaining smaller effective Newton's constant
at intermediate times, a feature that cannot be easily obtained in modified
gravity. In the second class of theories, which involve two extra propagating
degrees of freedom, we show that the $H_0$ tension can be alleviated, and the
mechanism behind it is the phantom behavior of the effective dark-energy
equation-of-state parameter. Hence, scalar-tensor and bi-scalar-tensor theories
have the capability of alleviating $H_0$ tension with both known sufficient
late-time mechanisms.
|
[
{
"created": "Wed, 30 Aug 2023 14:06:37 GMT",
"version": "v1"
}
] |
2023-08-31
|
[
[
"Petronikolou",
"Maria",
""
],
[
"Saridakis",
"Emmanuel N.",
""
]
] |
We investigate scalar-tensor and bi-scalar-tensor modified theories of gravity that can alleviate the $H_0$ tension. In the first class of theories we show that choosing particular models with shift-symmetric friction term we are able to alleviate the tension by obtaining smaller effective Newton's constant at intermediate times, a feature that cannot be easily obtained in modified gravity. In the second class of theories, which involve two extra propagating degrees of freedom, we show that the $H_0$ tension can be alleviated, and the mechanism behind it is the phantom behavior of the effective dark-energy equation-of-state parameter. Hence, scalar-tensor and bi-scalar-tensor theories have the capability of alleviating $H_0$ tension with both known sufficient late-time mechanisms.
|
1610.07467
|
Suddhasattwa Brahma
|
Jibril Ben Achour, Suddhasattwa Brahma, Julien Grain and Antonino
Marciano
|
A new look at scalar perturbations in loop quantum cosmology:
(un)deformed algebra approach using self dual variables
|
26 pages
| null | null | null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Scalar cosmological perturbations in loop quantum cosmology (LQC) is
revisited in a covariant manner, using self dual Ashtekar variables. For
real-valued Ashtekar-Barbero variables, this `deformed algebra' approach has
been shown to implement holonomy corrections from loop quantum gravity (LQG) in
a consistent manner, albeit deforming the algebra of modified constraints in
the process. This deformation has serious conceptual ramifications, not the
least of them being an effective `signature-change' in the deep quantum regime.
In this paper, we show that working with self dual variables lead to an
undeformed algebra of hypersurface deformations, even after including holonomy
corrections in the effective constraints. As a necessary consequence, the
diffeomorphism constraint picks up non-perturbative quantum corrections thus
hinting at a modification of the underlying space-time structure, a novel
ingredient compared to the usual treatment of (spatial) diffeomorphisms in LQG.
This work extends a similar result obtained in the context of spherically
symmetric gravity coupled to a scalar field, suggesting that self dual
variables could be better suited than their real counterparts to treat
inhomogeneous LQG models.
|
[
{
"created": "Mon, 24 Oct 2016 16:03:30 GMT",
"version": "v1"
}
] |
2016-10-25
|
[
[
"Achour",
"Jibril Ben",
""
],
[
"Brahma",
"Suddhasattwa",
""
],
[
"Grain",
"Julien",
""
],
[
"Marciano",
"Antonino",
""
]
] |
Scalar cosmological perturbations in loop quantum cosmology (LQC) is revisited in a covariant manner, using self dual Ashtekar variables. For real-valued Ashtekar-Barbero variables, this `deformed algebra' approach has been shown to implement holonomy corrections from loop quantum gravity (LQG) in a consistent manner, albeit deforming the algebra of modified constraints in the process. This deformation has serious conceptual ramifications, not the least of them being an effective `signature-change' in the deep quantum regime. In this paper, we show that working with self dual variables lead to an undeformed algebra of hypersurface deformations, even after including holonomy corrections in the effective constraints. As a necessary consequence, the diffeomorphism constraint picks up non-perturbative quantum corrections thus hinting at a modification of the underlying space-time structure, a novel ingredient compared to the usual treatment of (spatial) diffeomorphisms in LQG. This work extends a similar result obtained in the context of spherically symmetric gravity coupled to a scalar field, suggesting that self dual variables could be better suited than their real counterparts to treat inhomogeneous LQG models.
|
1411.4811
|
Mubasher Jamil
|
Bushra Majeed, Mubasher Jamil, Saqib Hussain
|
Particle Dynamics Around Weakly Magnetized Reissner-Nordstr\"{o}m Black
Hole
|
16 pages, 16 figures, version accepted for publication in 'Advances
in High Energy Physics'
|
Advances in High Energy Physics 2015 (2015) 671259
|
10.1155/2015/671259
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Considering the geometry of Reissner-Nordstr\"{o}m (RN) black hole immersed
in magnetic field we have studied the dynamics of neutral and charged
particles. A collision of particles in the inner stable circular orbit is
considered and the conditions for the escape of colliding particles from the
vicinity of black hole are given. The trajectories of the escaping particle are
discussed. Also the velocity required for this escape is calculated. It is
observed that there are more than one stable regions if magnetic field is
present in the accretion disk of black hole so the stability of ISCO increases
in the presence of magnetic field. Effect of magnetic field on the angular
motion of neutral and charged particles is observed graphically.
|
[
{
"created": "Tue, 18 Nov 2014 11:24:38 GMT",
"version": "v1"
},
{
"created": "Wed, 25 Nov 2015 10:19:19 GMT",
"version": "v2"
}
] |
2015-12-18
|
[
[
"Majeed",
"Bushra",
""
],
[
"Jamil",
"Mubasher",
""
],
[
"Hussain",
"Saqib",
""
]
] |
Considering the geometry of Reissner-Nordstr\"{o}m (RN) black hole immersed in magnetic field we have studied the dynamics of neutral and charged particles. A collision of particles in the inner stable circular orbit is considered and the conditions for the escape of colliding particles from the vicinity of black hole are given. The trajectories of the escaping particle are discussed. Also the velocity required for this escape is calculated. It is observed that there are more than one stable regions if magnetic field is present in the accretion disk of black hole so the stability of ISCO increases in the presence of magnetic field. Effect of magnetic field on the angular motion of neutral and charged particles is observed graphically.
|
0901.1773
|
Petr Tretyakov
|
Petr Tretyakov
|
Modified gravity with vacuum polarization
|
5 pages, 2 figures, in press, contribution to the anniversary volume
"The Problems of Modern Cosmology", on the occasion of the 50th birthday of
Prof. S. D. Odintsov. Editor: Prof. P. M. Lavrov, Tomsk State Pedagogical
University
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A brief review of cosmology in some generalized modified gravity theories
with vacuum polarization is presented. Stability question of de Sitter solution
is investigated.
|
[
{
"created": "Tue, 13 Jan 2009 12:22:40 GMT",
"version": "v1"
}
] |
2009-01-14
|
[
[
"Tretyakov",
"Petr",
""
]
] |
A brief review of cosmology in some generalized modified gravity theories with vacuum polarization is presented. Stability question of de Sitter solution is investigated.
|
2301.10848
|
Samuel Oliveira
|
Samuel W. P. Oliveira, Guilherme Y. Oyadomari, Ilya L. Shapiro
|
Pauli equation and charged spin-1/2 particle in a weak gravitational
field
|
21 pages, no figures
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Using the nonrelativistic approximation in the curved-space Dirac equation,
the analog of the Pauli equation is derived for a weak, but otherwise
arbitrary, gravitational field, in the presence of an electromagnetic field. On
top of that, are obtained the equations of motion for the massive spin-$1/2$
charged particle. In the two particular cases, we consider the previously
explored backgrounds of the plane gravitational wave and the homogeneous static
gravitational field. Different from the previous works which were employing
either the exact or conventional Foldy-Wouthuysen transformations, here we
perform calculations in the simplest way, in particular, aiming to clean up the
existing discrepancies in the literature.
|
[
{
"created": "Wed, 25 Jan 2023 22:14:33 GMT",
"version": "v1"
}
] |
2023-01-27
|
[
[
"Oliveira",
"Samuel W. P.",
""
],
[
"Oyadomari",
"Guilherme Y.",
""
],
[
"Shapiro",
"Ilya L.",
""
]
] |
Using the nonrelativistic approximation in the curved-space Dirac equation, the analog of the Pauli equation is derived for a weak, but otherwise arbitrary, gravitational field, in the presence of an electromagnetic field. On top of that, are obtained the equations of motion for the massive spin-$1/2$ charged particle. In the two particular cases, we consider the previously explored backgrounds of the plane gravitational wave and the homogeneous static gravitational field. Different from the previous works which were employing either the exact or conventional Foldy-Wouthuysen transformations, here we perform calculations in the simplest way, in particular, aiming to clean up the existing discrepancies in the literature.
|
2405.12449
|
Rubens R. S. Oliveira
|
R. R. S. Oliveira
|
Dirac fermions under rainbow gravity effects in the Bonnor-Melvin-Lambda
spacetime
|
12 pages, 3 figures, 2 tables. arXiv admin note: text overlap with
arXiv:2403.01366
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we study the relativistic energy spectrum for Dirac fermions
under rainbow gravity effects in the $(3+1)$-dimensional Bonnor-Melvin-Lambda
spacetime, where we work with the curved Dirac equation in cylindrical
coordinates. Using the tetrads formalism of General Relativity and considering
a first-order approximation for the trigonometric functions, we obtain a Bessel
equation. To solve this differential equation, we also consider a region where
a hard-wall confining potential is present (i.e., some finite distance where
the radial wave function is null). In other words, we define a second boundary
condition (Dirichlet boundary condition) to achieve the quantization of the
energy. Consequently, we obtain the spectrum for a fermion/antifermion, which
is quantized in terms of quantum numbers $n$, $m_j$ and $m_s$, where $n$ is the
radial quantum number, $m_j$ is the total magnetic quantum number, $m_s$ is the
spin magnetic quantum number, and explicitly depends on the rainbow functions
$F(\xi)$ and $G(\xi)$, curvature parameter $\alpha$, cosmological constant
$\Lambda$, fixed radius $r_0$, and on the rest energy $m_0$, and $z$-momentum
$p_z$. So, analyzing this spectrum according to the values of $m_j$ and $m_s$,
we see that for $m_j>0$ with $m_s=-1/2$ (positive angular momentum and spin
down), and for $m_j<0$ with $m_s=+1/2$ (negative angular momentum and spin up),
the spectrum is the same. Besides, we graphically analyze in detail the
behavior of the spectrum for the three scenarios of rainbow gravity as a
function of $\Lambda$, $r_0$, and $\alpha$ for three different values of $n$
(ground state and the first two excited states).
|
[
{
"created": "Tue, 21 May 2024 01:57:06 GMT",
"version": "v1"
}
] |
2024-05-22
|
[
[
"Oliveira",
"R. R. S.",
""
]
] |
In this paper, we study the relativistic energy spectrum for Dirac fermions under rainbow gravity effects in the $(3+1)$-dimensional Bonnor-Melvin-Lambda spacetime, where we work with the curved Dirac equation in cylindrical coordinates. Using the tetrads formalism of General Relativity and considering a first-order approximation for the trigonometric functions, we obtain a Bessel equation. To solve this differential equation, we also consider a region where a hard-wall confining potential is present (i.e., some finite distance where the radial wave function is null). In other words, we define a second boundary condition (Dirichlet boundary condition) to achieve the quantization of the energy. Consequently, we obtain the spectrum for a fermion/antifermion, which is quantized in terms of quantum numbers $n$, $m_j$ and $m_s$, where $n$ is the radial quantum number, $m_j$ is the total magnetic quantum number, $m_s$ is the spin magnetic quantum number, and explicitly depends on the rainbow functions $F(\xi)$ and $G(\xi)$, curvature parameter $\alpha$, cosmological constant $\Lambda$, fixed radius $r_0$, and on the rest energy $m_0$, and $z$-momentum $p_z$. So, analyzing this spectrum according to the values of $m_j$ and $m_s$, we see that for $m_j>0$ with $m_s=-1/2$ (positive angular momentum and spin down), and for $m_j<0$ with $m_s=+1/2$ (negative angular momentum and spin up), the spectrum is the same. Besides, we graphically analyze in detail the behavior of the spectrum for the three scenarios of rainbow gravity as a function of $\Lambda$, $r_0$, and $\alpha$ for three different values of $n$ (ground state and the first two excited states).
|
0801.1000
|
David Weld
|
D. M. Weld, J. Xia, B. Cabrera, A. Kapitulnik
|
A New Apparatus for Detecting Micron-Scale Deviations from Newtonian
Gravity
|
20 pages, 24 figures. Added references, edited discussion for clarity
|
Phys.Rev.D77:062006,2008
|
10.1103/PhysRevD.77.062006
| null |
gr-qc cond-mat.other hep-ph
| null |
We describe the design and construction of a new apparatus for detecting or
constraining deviations from Newtonian gravity at short length scales. The
apparatus consists of a new type of probe with rotary mass actuation and
cantilever-based force detection which is used to directly measure the force
between two micromachined masses separated by tens of microns. We present the
first data from the experiment, and discuss the prospects of more precisely
constraining or detecting non-Newtonian effects using this probe. Currently,
the sensitivity to attractive mass-dependent forces is equal to the best
existing limits at length scales near 5 microns. No non-Newtonian effects are
detected at that level.
|
[
{
"created": "Mon, 7 Jan 2008 14:37:07 GMT",
"version": "v1"
},
{
"created": "Tue, 12 Feb 2008 00:03:17 GMT",
"version": "v2"
}
] |
2008-11-26
|
[
[
"Weld",
"D. M.",
""
],
[
"Xia",
"J.",
""
],
[
"Cabrera",
"B.",
""
],
[
"Kapitulnik",
"A.",
""
]
] |
We describe the design and construction of a new apparatus for detecting or constraining deviations from Newtonian gravity at short length scales. The apparatus consists of a new type of probe with rotary mass actuation and cantilever-based force detection which is used to directly measure the force between two micromachined masses separated by tens of microns. We present the first data from the experiment, and discuss the prospects of more precisely constraining or detecting non-Newtonian effects using this probe. Currently, the sensitivity to attractive mass-dependent forces is equal to the best existing limits at length scales near 5 microns. No non-Newtonian effects are detected at that level.
|
2403.03965
|
Steven Balbus
|
Steven A. Balbus
|
Determining the difference between local acceleration and local gravity:
applications of the equivalence principle to relativistic trajectories
|
16 pages, 2 figures. Accepted for publication in the American Journal
of Physics
| null |
10.1119/5.0162082
| null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
We show by direct calculation that the common Equivalence Principle
explanation for why gravity must deflect light is quantitatively incorrect by a
factor of three in Schwarzschild geometry. It is therefore possible, at least
as a matter of principle, to tell the difference between local acceleration and
a true gravitational field by measuring the local deflection of light. We
calculate as well the deflection of test particles of arbitrary energy, and
construct a leading-order coordinate transformation from Schwarzschild to local
inertial coordinates, which shows explicitly how the effects of spatial
curvature manifest locally for relativistic trajectories of both finite and
vanishing rest mass particles.
|
[
{
"created": "Mon, 4 Mar 2024 21:26:07 GMT",
"version": "v1"
}
] |
2024-03-08
|
[
[
"Balbus",
"Steven A.",
""
]
] |
We show by direct calculation that the common Equivalence Principle explanation for why gravity must deflect light is quantitatively incorrect by a factor of three in Schwarzschild geometry. It is therefore possible, at least as a matter of principle, to tell the difference between local acceleration and a true gravitational field by measuring the local deflection of light. We calculate as well the deflection of test particles of arbitrary energy, and construct a leading-order coordinate transformation from Schwarzschild to local inertial coordinates, which shows explicitly how the effects of spatial curvature manifest locally for relativistic trajectories of both finite and vanishing rest mass particles.
|
1207.2660
|
Alessandro Fabbri
|
R. Balbinot, I. Carusotto, A. Fabbri, C. Mayoral, and A. Recati
|
Understanding Hawking radiation from simple models of atomic
Bose-Einstein condensates
|
41 pages. to appear in the proceedings of the IX SIGRAV School on
'Analogue Gravity', Como (Italy), May 2011
| null |
10.1007/978-3-319-00266-8_9
| null |
gr-qc cond-mat.quant-gas hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This chapter is an introduction to the Bogoliubov theory of dilute Bose
condensates as applied to the study of the spontaneous emission of phonons in a
stationary condensate flowing at supersonic speeds. This emission process is a
condensed-matter analog of Hawking radiation from astrophysical black holes but
is derived here from a microscopic quantum theory of the condensate without any
use of the analogy with gravitational systems. To facilitate physical
understanding of the basic concepts, a simple one-dimensional geometry with a
stepwise homogenous flow is considered which allows for a fully analytical
treatment.
|
[
{
"created": "Wed, 11 Jul 2012 14:50:45 GMT",
"version": "v1"
}
] |
2015-06-05
|
[
[
"Balbinot",
"R.",
""
],
[
"Carusotto",
"I.",
""
],
[
"Fabbri",
"A.",
""
],
[
"Mayoral",
"C.",
""
],
[
"Recati",
"A.",
""
]
] |
This chapter is an introduction to the Bogoliubov theory of dilute Bose condensates as applied to the study of the spontaneous emission of phonons in a stationary condensate flowing at supersonic speeds. This emission process is a condensed-matter analog of Hawking radiation from astrophysical black holes but is derived here from a microscopic quantum theory of the condensate without any use of the analogy with gravitational systems. To facilitate physical understanding of the basic concepts, a simple one-dimensional geometry with a stepwise homogenous flow is considered which allows for a fully analytical treatment.
|
gr-qc/0609017
|
Joan Sola
|
Julio C. Fabris, Ilya L. Shapiro, Joan Sola
|
Density Perturbations for Running Cosmological Constant
|
LaTeX, 21 pages, 5 figures. Extended discussion, references added.
Version accepted in JCAP
|
JCAP 0702:016,2007
|
10.1088/1475-7516/2007/02/016
|
UB-ECM-PF-06/14
|
gr-qc astro-ph hep-ph hep-th
| null |
The dynamics of density and metric perturbations is investigated for the
previously developed model where the decay of the vacuum energy into matter (or
vice versa) is due to the renormalization group (RG) running of the
cosmological constant (CC) term. The evolution of the CC depends on the single
parameter \nu, which characterizes the running of the CC produced by the
quantum effects of matter fields of the unknown high energy theory below the
Planck scale. The sign of \nu indicates whether bosons or fermions dominate in
the running. The spectrum of perturbations is computed assuming an adiabatic
regime and an isotropic stress tensor. Moreover, the perturbations of the CC
term are generated from the simplest covariant form suggested by the RG model
under consideration. The corresponding numerical analysis shows that for \nu>0
there is a depletion of the matter power spectrum at low scales (large wave
numbers) as compared to the standard LCDM model, whereas for \nu<0 there is an
excess of power at low scales. We find that the LSS data rule out the range
|\nu|> 10^{-4} while the values |\nu|< 10^{-6} look perfectly acceptable. For
\nu<0 the excess of power at low scales grows rapidly and the bound is more
severe. From the particle physics viewpoint, the values |\nu|\sim 10^{-6}
correspond to the ``desert'' in the mass spectrum above the GUT scale M_X\sim
10^{16} GeV. Our results are consistent with those obtained in other dynamical
models admitting an interaction between dark matter and dark energy. We find
that the matter power spectrum analysis is a highly efficient method to
discover a possible scale dependence of the vacuum energy.
|
[
{
"created": "Tue, 5 Sep 2006 23:39:18 GMT",
"version": "v1"
},
{
"created": "Wed, 13 Sep 2006 21:50:13 GMT",
"version": "v2"
},
{
"created": "Fri, 26 Jan 2007 19:46:29 GMT",
"version": "v3"
}
] |
2010-10-27
|
[
[
"Fabris",
"Julio C.",
""
],
[
"Shapiro",
"Ilya L.",
""
],
[
"Sola",
"Joan",
""
]
] |
The dynamics of density and metric perturbations is investigated for the previously developed model where the decay of the vacuum energy into matter (or vice versa) is due to the renormalization group (RG) running of the cosmological constant (CC) term. The evolution of the CC depends on the single parameter \nu, which characterizes the running of the CC produced by the quantum effects of matter fields of the unknown high energy theory below the Planck scale. The sign of \nu indicates whether bosons or fermions dominate in the running. The spectrum of perturbations is computed assuming an adiabatic regime and an isotropic stress tensor. Moreover, the perturbations of the CC term are generated from the simplest covariant form suggested by the RG model under consideration. The corresponding numerical analysis shows that for \nu>0 there is a depletion of the matter power spectrum at low scales (large wave numbers) as compared to the standard LCDM model, whereas for \nu<0 there is an excess of power at low scales. We find that the LSS data rule out the range |\nu|> 10^{-4} while the values |\nu|< 10^{-6} look perfectly acceptable. For \nu<0 the excess of power at low scales grows rapidly and the bound is more severe. From the particle physics viewpoint, the values |\nu|\sim 10^{-6} correspond to the ``desert'' in the mass spectrum above the GUT scale M_X\sim 10^{16} GeV. Our results are consistent with those obtained in other dynamical models admitting an interaction between dark matter and dark energy. We find that the matter power spectrum analysis is a highly efficient method to discover a possible scale dependence of the vacuum energy.
|
2001.11412
|
Geraint Pratten
|
Geraint Pratten, Sascha Husa, Cecilio Garcia-Quiros, Marta Colleoni,
Antoni Ramos-Buades, Hector Estelles, Rafel Jaume
|
Setting the cornerstone for the IMRPhenomX family of models for
gravitational waves from compact binaries: The dominant harmonic for
non-precessing quasi-circular black holes
|
29 pages. 20 figures. Comments and feedback welcome! This paper
corresponds to LIGO DCC P2000018
|
Phys. Rev. D 102, 064001 (2020)
|
10.1103/PhysRevD.102.064001
|
https://dcc.ligo.org/LIGO-P2000018
|
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we present IMRPhenomXAS, a thorough overhaul of the IMRPhenomD
[1,2] waveform model, which describes the dominant $l=2, \:| m | = 2$ spherical
harmonic mode of non-precessing coalescing black holes in terms of piecewise
closed form expressions in the frequency domain. Improvements include in
particular the accurate treatment of unequal spin effects, and the inclusion of
extreme mass ratio waveforms. IMRPhenomD has previously been extended to
approximately include spin precession [3] and subdominant spherical harmonics
[4], and with its extensions it has become a standard tool in gravitational
wave parameter estimation. Improved extensions of IMRPhenomXAS are discussed in
companion papers [5,6].
|
[
{
"created": "Thu, 30 Jan 2020 15:46:20 GMT",
"version": "v1"
}
] |
2020-09-09
|
[
[
"Pratten",
"Geraint",
""
],
[
"Husa",
"Sascha",
""
],
[
"Garcia-Quiros",
"Cecilio",
""
],
[
"Colleoni",
"Marta",
""
],
[
"Ramos-Buades",
"Antoni",
""
],
[
"Estelles",
"Hector",
""
],
[
"Jaume",
"Rafel",
""
]
] |
In this paper we present IMRPhenomXAS, a thorough overhaul of the IMRPhenomD [1,2] waveform model, which describes the dominant $l=2, \:| m | = 2$ spherical harmonic mode of non-precessing coalescing black holes in terms of piecewise closed form expressions in the frequency domain. Improvements include in particular the accurate treatment of unequal spin effects, and the inclusion of extreme mass ratio waveforms. IMRPhenomD has previously been extended to approximately include spin precession [3] and subdominant spherical harmonics [4], and with its extensions it has become a standard tool in gravitational wave parameter estimation. Improved extensions of IMRPhenomXAS are discussed in companion papers [5,6].
|
1712.06621
|
Sumanta Chakraborty
|
Karthik Rajeev, Sumanta Chakraborty and T. Padmanabhan
|
A comment on generalized Schwinger effect
|
published version
|
Eur. Phys. J. C 78, 836 (2018)
|
10.1140/epjc/s10052-018-6310-2
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A spatially homogeneous, time-dependent, electric field can produce charged
particle pairs from the vacuum. When the electric field is constant, the mean
number of pairs which are produced depends on the electric field and the
coupling constant in a non-analytic manner, showing that this result cannot be
obtained from the standard perturbation theory of quantum electrodynamics. When
the electric field varies with time and vanishes asymptotically, the result may
depend on the coupling constant either analytically or non-analytically. We
investigate the nature of this dependence in detail. We show that the
dependence of particle production on coupling constant is non-analytic for a
class of time-dependent electric fields which vanish asymptotically when a
specific condition is satisfied. We also demonstrate that for another class of
electric fields, which vary rapidly, the dependence of particle production on
coupling constant is analytic.
|
[
{
"created": "Mon, 18 Dec 2017 19:03:28 GMT",
"version": "v1"
},
{
"created": "Thu, 25 Oct 2018 07:29:03 GMT",
"version": "v2"
}
] |
2018-10-26
|
[
[
"Rajeev",
"Karthik",
""
],
[
"Chakraborty",
"Sumanta",
""
],
[
"Padmanabhan",
"T.",
""
]
] |
A spatially homogeneous, time-dependent, electric field can produce charged particle pairs from the vacuum. When the electric field is constant, the mean number of pairs which are produced depends on the electric field and the coupling constant in a non-analytic manner, showing that this result cannot be obtained from the standard perturbation theory of quantum electrodynamics. When the electric field varies with time and vanishes asymptotically, the result may depend on the coupling constant either analytically or non-analytically. We investigate the nature of this dependence in detail. We show that the dependence of particle production on coupling constant is non-analytic for a class of time-dependent electric fields which vanish asymptotically when a specific condition is satisfied. We also demonstrate that for another class of electric fields, which vary rapidly, the dependence of particle production on coupling constant is analytic.
|
0912.0708
|
Joel Franklin
|
S. Deser, J. Franklin
|
Circular Symmetry in Topologically Massive Gravity
|
amplified published version
|
Class.Quant.Grav 27:1007002,2010
|
10.1088/0264-9381/27/10/107002
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We re-derive, compactly, a TMG decoupling theorem: source-free TMG separates
into its Einstein and Cotton sectors for spaces with a hypersurface-orthogonal
Killing vector, here concretely for circular symmetry. We can then generalize
it to include matter, which is necessarily null.
|
[
{
"created": "Thu, 3 Dec 2009 20:42:16 GMT",
"version": "v1"
},
{
"created": "Mon, 28 Dec 2009 21:45:38 GMT",
"version": "v2"
},
{
"created": "Wed, 17 Mar 2010 22:14:51 GMT",
"version": "v3"
}
] |
2010-04-22
|
[
[
"Deser",
"S.",
""
],
[
"Franklin",
"J.",
""
]
] |
We re-derive, compactly, a TMG decoupling theorem: source-free TMG separates into its Einstein and Cotton sectors for spaces with a hypersurface-orthogonal Killing vector, here concretely for circular symmetry. We can then generalize it to include matter, which is necessarily null.
|
2110.08681
|
Kunal Lobo
|
Samuel E. Gralla and Kunal Lobo
|
Self-force effects in post-Minkowskian scattering
|
34 pages, 1 figure, corrected some equations from the previous
version
| null |
10.1088/1361-6382/ac5d88
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We revisit the old problem of the self-force on a particle moving in a
weak-field spacetime in the context of renewed interest in two-body
gravitational scattering. We analytically calculate the scalar,
electromagnetic, and gravitational self-force on a particle moving on a
straight-line trajectory at a large distance from a Newtonian star, and use
these results to find the associated correction to its motion. In the
gravitational case we must also include the matter-mediated force, which acts
at the same perturbative order as the gravitational self-force. We further
augment the gravitational results with geodesic calculations at second order in
the central body mass to determine the full, explicit solution to the two-body
gravitational scattering problem at second post-Minkowskian order (2PM). We
calculate the momentum transfer (which reproduces Westpfahl's old result), the
change in mechanical angular momentum (which matches the radiative flux
recently computed by Damour), and the change in mechanical mass moment (the
time-space components of the angular momentum tensor), which has not previously
appeared. Besides the new 2PM results of explicit trajectories and all
conserved quantities, this work clarifies the role of gravitational self-force
in PM scattering theory and provides a foundation for higher-order
calculations.
|
[
{
"created": "Sat, 16 Oct 2021 23:50:03 GMT",
"version": "v1"
},
{
"created": "Tue, 4 Jun 2024 21:37:47 GMT",
"version": "v2"
}
] |
2024-06-06
|
[
[
"Gralla",
"Samuel E.",
""
],
[
"Lobo",
"Kunal",
""
]
] |
We revisit the old problem of the self-force on a particle moving in a weak-field spacetime in the context of renewed interest in two-body gravitational scattering. We analytically calculate the scalar, electromagnetic, and gravitational self-force on a particle moving on a straight-line trajectory at a large distance from a Newtonian star, and use these results to find the associated correction to its motion. In the gravitational case we must also include the matter-mediated force, which acts at the same perturbative order as the gravitational self-force. We further augment the gravitational results with geodesic calculations at second order in the central body mass to determine the full, explicit solution to the two-body gravitational scattering problem at second post-Minkowskian order (2PM). We calculate the momentum transfer (which reproduces Westpfahl's old result), the change in mechanical angular momentum (which matches the radiative flux recently computed by Damour), and the change in mechanical mass moment (the time-space components of the angular momentum tensor), which has not previously appeared. Besides the new 2PM results of explicit trajectories and all conserved quantities, this work clarifies the role of gravitational self-force in PM scattering theory and provides a foundation for higher-order calculations.
|
1410.5950
|
Meng-Sen Ma
|
Meng-Sen Ma, Li-Chun Zhang, Hui-Hua Zhao, Ren Zhao
|
Phase transition of the higher dimensional charged Gauss-Bonnet black
hole in de Sitter spacetime
|
9 pages, 16 figures
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the phase transition of charged Gauss-Bonnet-de Sitter (GB-dS) black
hole. For black holes in de Sitter spacetime, there is not only black hole
horizon, but also the cosmological horizon. The thermodynamic quantities on the
both horizons satisfy the first law of the black hole thermodynamics,
respectively; moreover, there are additional connections between them. Using
the effective temperature approach, we obtained the effective thermodynamic
quantities of charged GB-dS black hole. According to Ehrenfest classification,
we calculate some response functions and plot their figures, from which one can
see that the spacetime undergoes a second-order phase transition at the
critical point. It is shown that the critical values of effective temperature
and pressure decrease with the increase of the value of GB parameter $\alpha$.
|
[
{
"created": "Wed, 22 Oct 2014 08:57:05 GMT",
"version": "v1"
}
] |
2014-10-23
|
[
[
"Ma",
"Meng-Sen",
""
],
[
"Zhang",
"Li-Chun",
""
],
[
"Zhao",
"Hui-Hua",
""
],
[
"Zhao",
"Ren",
""
]
] |
We study the phase transition of charged Gauss-Bonnet-de Sitter (GB-dS) black hole. For black holes in de Sitter spacetime, there is not only black hole horizon, but also the cosmological horizon. The thermodynamic quantities on the both horizons satisfy the first law of the black hole thermodynamics, respectively; moreover, there are additional connections between them. Using the effective temperature approach, we obtained the effective thermodynamic quantities of charged GB-dS black hole. According to Ehrenfest classification, we calculate some response functions and plot their figures, from which one can see that the spacetime undergoes a second-order phase transition at the critical point. It is shown that the critical values of effective temperature and pressure decrease with the increase of the value of GB parameter $\alpha$.
|
2101.08624
|
Alessandro Nagar
|
Alessandro Nagar, Alice Bonino, and Piero Rettegno
|
Effective one body multipolar waveform model for spin-aligned,
quasi-circular, eccentric, hyperbolic black hole binaries
|
23 pages, 21 figures. Improved version with additional appendix
reporting code performance. To appear in Phys. Rev. D
|
Phys. Rev. D 103, 104021 (2021)
|
10.1103/PhysRevD.103.104021
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Building upon recent work, we present an improved effective-one-body (EOB)
model for spin-aligned, coalescing, black hole binaries with generic orbital
configurations, i.e. quasi-circular, eccentric or hyperbolic orbits. The model
relies on the idea of incorporating general Newtonian prefactors, instead of
the usual quasi-circular ones, in both radiation reaction and waveform. The
major advance with respect to previous work is that the quasi-circular limit of
the model is now correctly informed by numerical relativity (NR) quasi-circular
simulation. This provides EOB/NR unfaithfulness for the dominant quadrupolar
waveform, calculated with Advanced LIGO noise, at most of the order of $1\%$
over a meaningful portion of the quasi-circular NR simulations calculated by
the Simulating eXtreme Spacetime (SXS) collaboration. In the presence of
eccentricity, the model is similarly NR-faithful, $\lesssim 1\%$, all over the
28 public SXS NR datasets, with initial eccentricity up to $\simeq 0.2$ , mass
ratio up to $q=3$ and dimensionless spin magnitudes as large as $+0.7$. Higher
multipoles, up to $\ell=5$ are also reliably modeled through the eccentric
inspiral, plunge merger and ringdown. For hyperbolic-like configurations, we
also show that the EOB computed scattering angle is in excellent agreement with
all currently available NR results.
|
[
{
"created": "Thu, 21 Jan 2021 14:13:36 GMT",
"version": "v1"
},
{
"created": "Tue, 26 Jan 2021 14:13:52 GMT",
"version": "v2"
},
{
"created": "Wed, 14 Apr 2021 09:07:41 GMT",
"version": "v3"
}
] |
2021-05-19
|
[
[
"Nagar",
"Alessandro",
""
],
[
"Bonino",
"Alice",
""
],
[
"Rettegno",
"Piero",
""
]
] |
Building upon recent work, we present an improved effective-one-body (EOB) model for spin-aligned, coalescing, black hole binaries with generic orbital configurations, i.e. quasi-circular, eccentric or hyperbolic orbits. The model relies on the idea of incorporating general Newtonian prefactors, instead of the usual quasi-circular ones, in both radiation reaction and waveform. The major advance with respect to previous work is that the quasi-circular limit of the model is now correctly informed by numerical relativity (NR) quasi-circular simulation. This provides EOB/NR unfaithfulness for the dominant quadrupolar waveform, calculated with Advanced LIGO noise, at most of the order of $1\%$ over a meaningful portion of the quasi-circular NR simulations calculated by the Simulating eXtreme Spacetime (SXS) collaboration. In the presence of eccentricity, the model is similarly NR-faithful, $\lesssim 1\%$, all over the 28 public SXS NR datasets, with initial eccentricity up to $\simeq 0.2$ , mass ratio up to $q=3$ and dimensionless spin magnitudes as large as $+0.7$. Higher multipoles, up to $\ell=5$ are also reliably modeled through the eccentric inspiral, plunge merger and ringdown. For hyperbolic-like configurations, we also show that the EOB computed scattering angle is in excellent agreement with all currently available NR results.
|
1410.0352
|
Seyed Hossein Hendi Dr.
|
S. H. Hendi, S. Panahiyan and B. Eslam Panah
|
$P-V$ criticality and geometrothermodynamics of black holes with
Born-Infeld type nonlinear electrodynamics
|
Two new sections and more clarifications are added; minor changes in
title; 15 pages with 12 figures
|
International Journal of Modern Physics D Vol. 25, No. 1 (2016)
1650010
|
10.1142/S0218271816500103
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, we take into account the black hole solutions of Einstein
gravity with logarithmic and exponential forms of nonlinear electrodynamics. We
consider $\Lambda$ as a dynamical pressure to study the analogy of the black
holes with the Van der Waals system. We plot P-v, T-v and G-T diagrams and
investigate the phase transition of adS black holes in the canonical ensemble.
We study the nonlinearity effects of electrodynamics and see how the power of
nonlinearity affects critical behavior. We also investigate the effects of
dimensionality on the critical values and analyze its crucial role. Moreover,
we show the changes in the universal ratio P_{c}v_{c}/T_{c} for variation of
different parameters. In addition, we make a comparison between linear and
nonlinear electrodynamics and show that the lowest critical temperature belongs
to Maxwell theory. Also, we make some arguments regarding to how power of
nonlinearity brings the system to Schwarzschild-like and
Reissner-Nordstrom-like limitations. Next, we study the critical behavior in
context of heat capacity. We show that critical behavior of system is similar
to one in phase diagrams of extended phase space. We point out that phase
transition points of the extended phase space only appear as divergencies of
heat capacity. We also extend the study of phase transitions through GTD
method. We introduce two new metrics and show that divergencies of TRS of the
new metrics coincide with phase transitions. The characteristic behavior of
these divergencies, hence critical points is exactly the one that is obtained
in extended phase space and heat capacity. We also introduce a new method for
obtaining critical pressure and horizon radius by considering denominator of
the heat capacity. We show that there are several benefits that make this
approach favorable comparing to other ones.
|
[
{
"created": "Wed, 1 Oct 2014 02:28:21 GMT",
"version": "v1"
},
{
"created": "Thu, 9 Oct 2014 18:18:19 GMT",
"version": "v2"
},
{
"created": "Wed, 24 Jun 2015 07:13:50 GMT",
"version": "v3"
}
] |
2015-11-25
|
[
[
"Hendi",
"S. H.",
""
],
[
"Panahiyan",
"S.",
""
],
[
"Panah",
"B. Eslam",
""
]
] |
In this paper, we take into account the black hole solutions of Einstein gravity with logarithmic and exponential forms of nonlinear electrodynamics. We consider $\Lambda$ as a dynamical pressure to study the analogy of the black holes with the Van der Waals system. We plot P-v, T-v and G-T diagrams and investigate the phase transition of adS black holes in the canonical ensemble. We study the nonlinearity effects of electrodynamics and see how the power of nonlinearity affects critical behavior. We also investigate the effects of dimensionality on the critical values and analyze its crucial role. Moreover, we show the changes in the universal ratio P_{c}v_{c}/T_{c} for variation of different parameters. In addition, we make a comparison between linear and nonlinear electrodynamics and show that the lowest critical temperature belongs to Maxwell theory. Also, we make some arguments regarding to how power of nonlinearity brings the system to Schwarzschild-like and Reissner-Nordstrom-like limitations. Next, we study the critical behavior in context of heat capacity. We show that critical behavior of system is similar to one in phase diagrams of extended phase space. We point out that phase transition points of the extended phase space only appear as divergencies of heat capacity. We also extend the study of phase transitions through GTD method. We introduce two new metrics and show that divergencies of TRS of the new metrics coincide with phase transitions. The characteristic behavior of these divergencies, hence critical points is exactly the one that is obtained in extended phase space and heat capacity. We also introduce a new method for obtaining critical pressure and horizon radius by considering denominator of the heat capacity. We show that there are several benefits that make this approach favorable comparing to other ones.
|
gr-qc/9409041
|
G. Rein
|
Gerhard Rein
|
Cosmological solutions of the Vlasov-Einstein system with spherical,
plane, and hyperbolic symmetry
|
32 pages, LaTeX, report 941
|
Math.Proc.Cambridge Phil.Soc. 119 (1996) 739-762
|
10.1017/S0305004100074569
| null |
gr-qc
| null |
The Vlasov-Einstein system describes a self-gravitating, collisionless gas
within the framework of general relativity. We investigate the initial value
problem in a cosmological setting with spherical, plane, or hyperbolic symmetry
and prove that for small initial data solutions exist up to a spacetime
singularity which is a curvature and a crushing singularity. An important tool
in the analysis is a local existence result with a continuation criterion
saying that solutions can be extended as long as the momenta in the support of
the phase-space distribution of the matter remain bounded.
|
[
{
"created": "Tue, 20 Sep 1994 08:14:19 GMT",
"version": "v1"
}
] |
2015-06-25
|
[
[
"Rein",
"Gerhard",
""
]
] |
The Vlasov-Einstein system describes a self-gravitating, collisionless gas within the framework of general relativity. We investigate the initial value problem in a cosmological setting with spherical, plane, or hyperbolic symmetry and prove that for small initial data solutions exist up to a spacetime singularity which is a curvature and a crushing singularity. An important tool in the analysis is a local existence result with a continuation criterion saying that solutions can be extended as long as the momenta in the support of the phase-space distribution of the matter remain bounded.
|
gr-qc/9702002
|
Luis Lehner
|
R. Gomez, L. Lehner, P. Papadopoulos and J. Winicour
|
The eth formalism in numerical relativity
|
18 pages. To be published in Class. Quantum Grav
|
Class.Quant.Grav. 14 (1997) 977-990
|
10.1088/0264-9381/14/4/013
| null |
gr-qc
| null |
We present a finite difference version of the eth formalism, which allows use
of tensor fields in spherical coordinates in a manner which avoids polar
singularities. The method employs two overlapping stereographic coordinate
patches, with interpolations between the patches in the regions of overlap. It
provides a new and effective computational tool for dealing with a wide variety
of systems in which spherical coordinates are natural, such as the generation
of radiation from an isolated source. We test the formalism with the evolution
of waves in three spatial dimensions and the calculation of the curvature
scalar of arbitrarily curved geometries on topologically spherical manifolds.
The formalism is applied to the solution of the Robinson-Trautman equation and
reveals some new features of gravitational waveforms in the nonlinear regime.
|
[
{
"created": "Fri, 31 Jan 1997 16:03:26 GMT",
"version": "v1"
}
] |
2009-10-30
|
[
[
"Gomez",
"R.",
""
],
[
"Lehner",
"L.",
""
],
[
"Papadopoulos",
"P.",
""
],
[
"Winicour",
"J.",
""
]
] |
We present a finite difference version of the eth formalism, which allows use of tensor fields in spherical coordinates in a manner which avoids polar singularities. The method employs two overlapping stereographic coordinate patches, with interpolations between the patches in the regions of overlap. It provides a new and effective computational tool for dealing with a wide variety of systems in which spherical coordinates are natural, such as the generation of radiation from an isolated source. We test the formalism with the evolution of waves in three spatial dimensions and the calculation of the curvature scalar of arbitrarily curved geometries on topologically spherical manifolds. The formalism is applied to the solution of the Robinson-Trautman equation and reveals some new features of gravitational waveforms in the nonlinear regime.
|
1602.07192
|
Sergey Yu. Vernov
|
Alexander Yu. Kamenshchik, Ekaterina O. Pozdeeva, Sergey Yu. Vernov,
Alessandro Tronconi, Giovanni Venturi
|
Transformations between Jordan and Einstein frames: Bounces,
antigravity, and crossing singularities
|
15 pages, v2: title changed, presentation improved, references added,
accepted for publication in Phys. Rev. D
|
Phys. Rev. D 94 (2016) 063510
|
10.1103/PhysRevD.94.063510
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the relation between the Jordan-Einstein frame transition and the
possible description of the crossing of singularities in flat Friedmann
universes, using the fact that the regular evolution in one frame can
correspond to crossing singularities in the other frame. We show that some
interesting effects arise in simple models such as one with a massless scalar
field or another wherein the potential is constant in the Einstein frame. The
dynamics in these models and in their conformally coupled counterparts are
described in detail, and a method for the continuation of such cosmological
evolutions beyond the singularity is developed. We compare our approach with
some other, recently developed, approaches to the problem of the crossing of
singularities.
|
[
{
"created": "Tue, 23 Feb 2016 15:27:09 GMT",
"version": "v1"
},
{
"created": "Tue, 13 Sep 2016 18:27:45 GMT",
"version": "v2"
}
] |
2016-09-14
|
[
[
"Kamenshchik",
"Alexander Yu.",
""
],
[
"Pozdeeva",
"Ekaterina O.",
""
],
[
"Vernov",
"Sergey Yu.",
""
],
[
"Tronconi",
"Alessandro",
""
],
[
"Venturi",
"Giovanni",
""
]
] |
We study the relation between the Jordan-Einstein frame transition and the possible description of the crossing of singularities in flat Friedmann universes, using the fact that the regular evolution in one frame can correspond to crossing singularities in the other frame. We show that some interesting effects arise in simple models such as one with a massless scalar field or another wherein the potential is constant in the Einstein frame. The dynamics in these models and in their conformally coupled counterparts are described in detail, and a method for the continuation of such cosmological evolutions beyond the singularity is developed. We compare our approach with some other, recently developed, approaches to the problem of the crossing of singularities.
|
gr-qc/9607051
|
S. R. Schreckenberg
|
S. Schreckenberg
|
Symmetry and History Quantum Theory: An analogue of Wigner's Theorem
|
To appear in Jour.Math.Phys.; 25 pages; Latex-document
|
J.Math.Phys. 37 (1996) 6086-6105
|
10.1063/1.531765
|
Imperial/TP/95-96/40
|
gr-qc quant-ph
| null |
The basic ingredients of the `consistent histories' approach to quantum
theory are a space $\UP$ of `history propositions' and a space $\D$ of
`decoherence functionals'. In this article we consider such history quantum
theories in the case where $\UP$ is given by the set of projectors $\P(\V)$ on
some Hilbert space $\V$. We define the notion of a `physical symmetry of a
history quantum theory' (PSHQT) and specify such objects exhaustively with the
aid of an analogue of Wigner's theorem. In order to prove this theorem we
investigate the structure of $\D$, define the notion of an `elementary
decoherence functional' and show that each decoherence functional can be
expanded as a certain combination of these functionals. We call two history
quantum theories that are related by a PSHQT `physically equivalent' and show
explicitly, in the case of history quantum mechanics, how this notion is
compatible with one that has appeared previously.
|
[
{
"created": "Tue, 23 Jul 1996 13:00:40 GMT",
"version": "v1"
}
] |
2009-10-28
|
[
[
"Schreckenberg",
"S.",
""
]
] |
The basic ingredients of the `consistent histories' approach to quantum theory are a space $\UP$ of `history propositions' and a space $\D$ of `decoherence functionals'. In this article we consider such history quantum theories in the case where $\UP$ is given by the set of projectors $\P(\V)$ on some Hilbert space $\V$. We define the notion of a `physical symmetry of a history quantum theory' (PSHQT) and specify such objects exhaustively with the aid of an analogue of Wigner's theorem. In order to prove this theorem we investigate the structure of $\D$, define the notion of an `elementary decoherence functional' and show that each decoherence functional can be expanded as a certain combination of these functionals. We call two history quantum theories that are related by a PSHQT `physically equivalent' and show explicitly, in the case of history quantum mechanics, how this notion is compatible with one that has appeared previously.
|
1707.06459
|
Abdel Nasser Tawfik
|
A. Tawfik, A. Diab (Egyptian Ctr. Theor. Phys., Cairo, WLCAPP, Cairo),
E. Abou El Dahab (Egyptian Ctr. Theor. Phys., Cairo, MUTI, Cairo)
|
Minimal-supersymmetric extended inflation field in Horava-Lifshitz
gravity
|
21 pages, 5 figures, accepted for publication in IJMPD
|
International Journal of Modern Physics D Vol. 26 (2017) 1750166
(16 pages)
|
10.1142/S0218271817501668
|
ECTP-2016-16, WLCAPP-2016-16
|
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the Friedmann inflation in general covariant Horava-Lifshitz (HL)
gravity without the projectability conditions and with detailed and
non-detailed balance conditions. Accordingly, we derive modifications in the
Friedmann equations due to a single-scalar field potential describing
minimal-supersymmetrically extended inflation. By implementing two
time-independent equations of state (EoS) characterizing the cosmic background
geometry filled up with dark energy, the dependence of the tensorial and scalar
density fluctuations and their ratios on the inflation field are determined.
The latter refer to the time evolution of the inflationary field relative to
the Hubble parameter. Furthermore, the ratios of tensorial-to-spectral density
fluctuations are calculated in dependence on the spectral index. For cold dark
energy EoS $\omega=-1/3$, we find that the tensorial-to-spectral density
fluctuations are not depending on the different theories of gravity and the
results are very small relative to the recent BICEP2/Keck Array-Planck
observations, $10^{-9} \lessapprox r \lessapprox 10^{-3}$. We have also
calculated the tensorial and scalar perturbations of the primordial spectra.
|
[
{
"created": "Wed, 19 Jul 2017 12:51:44 GMT",
"version": "v1"
}
] |
2017-12-04
|
[
[
"Tawfik",
"A.",
"",
"Egyptian Ctr. Theor. Phys., Cairo, WLCAPP, Cairo"
],
[
"Diab",
"A.",
"",
"Egyptian Ctr. Theor. Phys., Cairo, WLCAPP, Cairo"
],
[
"Dahab",
"E. Abou El",
"",
"Egyptian Ctr. Theor. Phys., Cairo, MUTI, Cairo"
]
] |
We study the Friedmann inflation in general covariant Horava-Lifshitz (HL) gravity without the projectability conditions and with detailed and non-detailed balance conditions. Accordingly, we derive modifications in the Friedmann equations due to a single-scalar field potential describing minimal-supersymmetrically extended inflation. By implementing two time-independent equations of state (EoS) characterizing the cosmic background geometry filled up with dark energy, the dependence of the tensorial and scalar density fluctuations and their ratios on the inflation field are determined. The latter refer to the time evolution of the inflationary field relative to the Hubble parameter. Furthermore, the ratios of tensorial-to-spectral density fluctuations are calculated in dependence on the spectral index. For cold dark energy EoS $\omega=-1/3$, we find that the tensorial-to-spectral density fluctuations are not depending on the different theories of gravity and the results are very small relative to the recent BICEP2/Keck Array-Planck observations, $10^{-9} \lessapprox r \lessapprox 10^{-3}$. We have also calculated the tensorial and scalar perturbations of the primordial spectra.
|
2209.11541
|
Ouali Taoufik
|
Brahim Asfour, Aatifa Bargach, Ahmed Errahmani, and Taoufik Ouali
|
Higgs inflation model with non-minimal coupling in hybrid Palatini
approach
|
9 pages, 4 figures
|
Chinese Physics C Vol. 48, No. 4 (2024) 045104
|
10.1088/1674-1137/ad1dcd
| null |
gr-qc
|
http://creativecommons.org/licenses/by/4.0/
|
The inflation model with non-minimal coupling scalar field in the context of
the hybrid metric Palatini is studied in this paper. We derive the Einstein's
field equations, the equations of motion of the scalar field. Furthermore,the
background and the perturbative parameters are obtained by means of Friedmann
equation in the slow roll regime. The analysis of cosmological perturbations
allowed us to obtain the main inflationary parameters such as the scalar
spectral index $n_s$ and the tensor to scalar ratio $r$. In this perspective,
as an application of our analysis, we consider the Higgs field with quartic
potential which plays the inflaton role, and we show that the predictions of
Higgs hybrid inflation are in good agreement with recent observational data
\cite{Akrami:2018odb}.
|
[
{
"created": "Fri, 23 Sep 2022 12:00:13 GMT",
"version": "v1"
},
{
"created": "Wed, 28 Feb 2024 13:43:43 GMT",
"version": "v2"
}
] |
2024-02-29
|
[
[
"Asfour",
"Brahim",
""
],
[
"Bargach",
"Aatifa",
""
],
[
"Errahmani",
"Ahmed",
""
],
[
"Ouali",
"Taoufik",
""
]
] |
The inflation model with non-minimal coupling scalar field in the context of the hybrid metric Palatini is studied in this paper. We derive the Einstein's field equations, the equations of motion of the scalar field. Furthermore,the background and the perturbative parameters are obtained by means of Friedmann equation in the slow roll regime. The analysis of cosmological perturbations allowed us to obtain the main inflationary parameters such as the scalar spectral index $n_s$ and the tensor to scalar ratio $r$. In this perspective, as an application of our analysis, we consider the Higgs field with quartic potential which plays the inflaton role, and we show that the predictions of Higgs hybrid inflation are in good agreement with recent observational data \cite{Akrami:2018odb}.
|
gr-qc/0611064
|
Valery Kiselev
|
V.V.Kiselev
|
Scaling attractors for quintessence in flat universe with cosmological
term
|
11 pages, 16 eps-figures, revtex4, reference with comment added
|
JCAP0801:019,2008
|
10.1088/1475-7516/2008/01/019
| null |
gr-qc
| null |
For evolution of flat universe, we classify late time and future attractors
with scaling behavior of scalar field quintessence in the case of potential,
which, at definite values of its parameters and initial data, corresponds to
exact scaling in the presence of cosmological constant.
|
[
{
"created": "Mon, 13 Nov 2006 07:36:01 GMT",
"version": "v1"
},
{
"created": "Tue, 21 Nov 2006 12:35:49 GMT",
"version": "v2"
},
{
"created": "Thu, 8 Feb 2007 11:55:21 GMT",
"version": "v3"
}
] |
2008-11-26
|
[
[
"Kiselev",
"V. V.",
""
]
] |
For evolution of flat universe, we classify late time and future attractors with scaling behavior of scalar field quintessence in the case of potential, which, at definite values of its parameters and initial data, corresponds to exact scaling in the presence of cosmological constant.
|
0804.2931
|
Hongsheng Zhang
|
Hongsheng Zhang, Hyerim Noh and Zong-Hong Zhu
|
A new class of plane symmetric solution
|
10 pages, v2: a typo in equation (37) corrected, v3: equation (68)
corrected, PLB V663, Pages 291-296
|
Phys.Lett.B663:291-296,2008
|
10.1016/j.physletb.2008.04.022
| null |
gr-qc astro-ph hep-th math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A new class of static plane symmetric solution of Einstein field equation
generated by a perfect fluid source is put forward. A special family of this
new solution is investigated in detail. The constraints on the parameters by
different energy conditions are studied. The classical stability of this
solution is discussed. The junction conditions matching to Minkowski metric and
Taub metric are analyzed respectively.
|
[
{
"created": "Fri, 18 Apr 2008 02:53:02 GMT",
"version": "v1"
},
{
"created": "Tue, 13 May 2008 00:44:54 GMT",
"version": "v2"
},
{
"created": "Wed, 1 Apr 2009 05:31:56 GMT",
"version": "v3"
}
] |
2009-04-01
|
[
[
"Zhang",
"Hongsheng",
""
],
[
"Noh",
"Hyerim",
""
],
[
"Zhu",
"Zong-Hong",
""
]
] |
A new class of static plane symmetric solution of Einstein field equation generated by a perfect fluid source is put forward. A special family of this new solution is investigated in detail. The constraints on the parameters by different energy conditions are studied. The classical stability of this solution is discussed. The junction conditions matching to Minkowski metric and Taub metric are analyzed respectively.
|
0901.3762
|
Rubab Khan
|
Rubab Khan, Shourov Chatterji
|
Enhancing the capabilities of LIGO time-frequency plane searches through
clustering
|
17 pages, 6 figures. Submitted to CQG on Dec 12, 2008; accepted on
June 18, 2009
|
Class.Quant.Grav.26:155009,2009
|
10.1088/0264-9381/26/15/155009
| null |
gr-qc astro-ph.IM cs.CV physics.data-an
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
One class of gravitational wave signals LIGO is searching for consists of
short duration bursts of unknown waveforms. Potential sources include core
collapse supernovae, gamma ray burst progenitors, and mergers of binary black
holes or neutron stars. We present a density-based clustering algorithm to
improve the performance of time-frequency searches for such gravitational-wave
bursts when they are extended in time and/or frequency, and not sufficiently
well known to permit matched filtering. We have implemented this algorithm as
an extension to the QPipeline, a gravitational-wave data analysis pipeline for
the detection of bursts, which currently determines the statistical
significance of events based solely on the peak significance observed in
minimum uncertainty regions of the time-frequency plane. Density based
clustering improves the performance of such a search by considering the
aggregate significance of arbitrarily shaped regions in the time-frequency
plane and rejecting the isolated minimum uncertainty features expected from the
background detector noise. In this paper, we present test results for simulated
signals and demonstrate that density based clustering improves the performance
of the QPipeline for signals extended in time and/or frequency.
|
[
{
"created": "Fri, 23 Jan 2009 20:59:45 GMT",
"version": "v1"
},
{
"created": "Fri, 23 Jan 2009 21:41:46 GMT",
"version": "v2"
},
{
"created": "Thu, 18 Jun 2009 20:12:08 GMT",
"version": "v3"
}
] |
2009-07-22
|
[
[
"Khan",
"Rubab",
""
],
[
"Chatterji",
"Shourov",
""
]
] |
One class of gravitational wave signals LIGO is searching for consists of short duration bursts of unknown waveforms. Potential sources include core collapse supernovae, gamma ray burst progenitors, and mergers of binary black holes or neutron stars. We present a density-based clustering algorithm to improve the performance of time-frequency searches for such gravitational-wave bursts when they are extended in time and/or frequency, and not sufficiently well known to permit matched filtering. We have implemented this algorithm as an extension to the QPipeline, a gravitational-wave data analysis pipeline for the detection of bursts, which currently determines the statistical significance of events based solely on the peak significance observed in minimum uncertainty regions of the time-frequency plane. Density based clustering improves the performance of such a search by considering the aggregate significance of arbitrarily shaped regions in the time-frequency plane and rejecting the isolated minimum uncertainty features expected from the background detector noise. In this paper, we present test results for simulated signals and demonstrate that density based clustering improves the performance of the QPipeline for signals extended in time and/or frequency.
|
2210.03631
|
Tiberiu Harko
|
Tiberiu Harko, Shahab Shahidi
|
Palatini formulation of the conformally invariant $f\left(R, L_m\right)$
gravity theory
|
17 pages, 6 figures, accepted for publication in EPJC
| null |
10.1140/epjc/s10052-022-10891-z
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We investigate the field equations of the conformally invariant models of
gravity with curvature-matter coupling, constructed in Weyl geometry, by using
the Palatini formalism. We consider the case in which the Lagrangian is given
by the sum of the square of the Weyl scalar, of the strength of the field
associated to the Weyl vector, and a conformally invariant geometry-matter
coupling term, constructed from the matter Lagrangian and the Weyl scalar.
After substituting the Weyl scalar in terms of its Riemannian counterpart, the
quadratic action is defined in Riemann geometry, and involves a nonminimal
coupling between the Ricci scalar and the matter Lagrangian. For the sake of
generality, a more general Lagrangian, in which the Weyl vector is nonminmally
coupled with an arbitrary function of the Ricci scalar, is also considered. By
varying the action independently with respect to the metric and the connection,
the independent connection can be expressed as the Levi-Civita connection of an
auxiliary, Ricci scalar and Weyl vector dependent metric, which is related to
the physical metric by means of a conformal transformation. The field equations
are obtained in both the metric and the Palatini formulations. The cosmological
implications of the Palatini field equations are investigated for three
distinct models corresponding to different forms of the coupling functions. A
comparison with the standard $\Lambda$CDM model is also performed, and we find
that the Palatini type cosmological models can give an acceptable description
of the observations.
|
[
{
"created": "Fri, 7 Oct 2022 15:35:48 GMT",
"version": "v1"
}
] |
2022-11-23
|
[
[
"Harko",
"Tiberiu",
""
],
[
"Shahidi",
"Shahab",
""
]
] |
We investigate the field equations of the conformally invariant models of gravity with curvature-matter coupling, constructed in Weyl geometry, by using the Palatini formalism. We consider the case in which the Lagrangian is given by the sum of the square of the Weyl scalar, of the strength of the field associated to the Weyl vector, and a conformally invariant geometry-matter coupling term, constructed from the matter Lagrangian and the Weyl scalar. After substituting the Weyl scalar in terms of its Riemannian counterpart, the quadratic action is defined in Riemann geometry, and involves a nonminimal coupling between the Ricci scalar and the matter Lagrangian. For the sake of generality, a more general Lagrangian, in which the Weyl vector is nonminmally coupled with an arbitrary function of the Ricci scalar, is also considered. By varying the action independently with respect to the metric and the connection, the independent connection can be expressed as the Levi-Civita connection of an auxiliary, Ricci scalar and Weyl vector dependent metric, which is related to the physical metric by means of a conformal transformation. The field equations are obtained in both the metric and the Palatini formulations. The cosmological implications of the Palatini field equations are investigated for three distinct models corresponding to different forms of the coupling functions. A comparison with the standard $\Lambda$CDM model is also performed, and we find that the Palatini type cosmological models can give an acceptable description of the observations.
|
1210.5922
|
Branislav Nikoli\'c
|
Branislav D. Nikoli\'c, Milan R. Panti\'c
|
A Possible Intuitive Derivation of the Kerr Metric in Orthogonal Form
Based On Ellipsoidal Metric Ansatz
|
Corrected version, argument for the reciprocal relation between
time-time and radial-radial metric tensor component emphasized and cited, 3
new references added; 19 pages, 11 references, 1 table
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper we show that it is possible to derive the Kerr solution in an
alternative, intuitive way, based on physical reasoning and starting from an
orthogonal metric ansatz having manifest ellipsoidal space-time symmetry
(ellipsoidal symmetry). This is possible because both flat metric in oblate
spheroidal (ellipsoidal) coordinates and Kerr metric in Boyer-Lindquist
coordinates can be rewritten in such a form that the difference between the two
is only in the time-time and radial-radial metric tensor components, just as is
the case with Schwarzschild metric and flat metric in spherical coordinates.
|
[
{
"created": "Mon, 22 Oct 2012 15:08:46 GMT",
"version": "v1"
},
{
"created": "Tue, 5 Mar 2013 17:21:42 GMT",
"version": "v2"
}
] |
2013-03-06
|
[
[
"Nikolić",
"Branislav D.",
""
],
[
"Pantić",
"Milan R.",
""
]
] |
In this paper we show that it is possible to derive the Kerr solution in an alternative, intuitive way, based on physical reasoning and starting from an orthogonal metric ansatz having manifest ellipsoidal space-time symmetry (ellipsoidal symmetry). This is possible because both flat metric in oblate spheroidal (ellipsoidal) coordinates and Kerr metric in Boyer-Lindquist coordinates can be rewritten in such a form that the difference between the two is only in the time-time and radial-radial metric tensor components, just as is the case with Schwarzschild metric and flat metric in spherical coordinates.
|
2101.05973
|
Jose Socorro Garcia
|
Luis Rey D\'iaz-Barr\'on, Abraham Espinoza-Garc\'ia, S.
P\'erez-Pay\'an, and J. Socorro
|
Anisotropic chiral cosmology: exact solutions
|
23 pages, 4 figures, The names are put as appear published in the
IJMPD, we add some references. arXiv admin note: text overlap with
arXiv:2012.11108
| null |
10.1142/S0218271821500802
| null |
gr-qc math-ph math.MP
|
http://creativecommons.org/publicdomain/zero/1.0/
|
In this work, we investigate the anisotropic Bianchi type I cosmological
model in the chiral setup, in a twofold manner. Firstly, we consider a
quintessence plus a k-essence like model, where two scalar fields but only one
potential term is considered. Secondly, we look at a model where in addition to
the two scalar fields the two potential terms are taken into account as well as
the standard kinetic energy and the mixed term. Regarding this second model, it
is shown that two possible cases can be studied: a quintom like case and a
quintessence like case. In each of the models, we were able to find both
classical and quantum analytical solutions.
|
[
{
"created": "Fri, 15 Jan 2021 05:42:28 GMT",
"version": "v1"
},
{
"created": "Sun, 27 Jun 2021 15:00:49 GMT",
"version": "v2"
}
] |
2021-06-29
|
[
[
"Díaz-Barrón",
"Luis Rey",
""
],
[
"Espinoza-García",
"Abraham",
""
],
[
"Pérez-Payán",
"S.",
""
],
[
"Socorro",
"J.",
""
]
] |
In this work, we investigate the anisotropic Bianchi type I cosmological model in the chiral setup, in a twofold manner. Firstly, we consider a quintessence plus a k-essence like model, where two scalar fields but only one potential term is considered. Secondly, we look at a model where in addition to the two scalar fields the two potential terms are taken into account as well as the standard kinetic energy and the mixed term. Regarding this second model, it is shown that two possible cases can be studied: a quintom like case and a quintessence like case. In each of the models, we were able to find both classical and quantum analytical solutions.
|
1710.06195
|
Benjamin Bahr
|
Benjamin Bahr, Vadim Belov
|
On the volume simplicity constraint in the EPRL spin foam model
|
14 pages, 5 figures
|
Phys. Rev. D 97, 086009 (2018)
|
10.1103/PhysRevD.97.086009
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We propose a quantum version of the quadratic volume simplicity constraint
for the EPRL spin foam model. It relies on a formula for the volume of
4-dimensional polyhedra, depending on its bivectors and the knotting class of
its boundary graph. While this leads to no further condition for the 4-simplex,
the constraint becomes non-trivial for more complicated boundary graphs. We
show that, in the semi-classical limit of the hypercuboidal graph, the
constraint turns into the geometricity condition observed recently by several
authors.
|
[
{
"created": "Tue, 17 Oct 2017 10:26:52 GMT",
"version": "v1"
}
] |
2018-04-25
|
[
[
"Bahr",
"Benjamin",
""
],
[
"Belov",
"Vadim",
""
]
] |
We propose a quantum version of the quadratic volume simplicity constraint for the EPRL spin foam model. It relies on a formula for the volume of 4-dimensional polyhedra, depending on its bivectors and the knotting class of its boundary graph. While this leads to no further condition for the 4-simplex, the constraint becomes non-trivial for more complicated boundary graphs. We show that, in the semi-classical limit of the hypercuboidal graph, the constraint turns into the geometricity condition observed recently by several authors.
|
gr-qc/0005064
|
Alicia M. Sintes
|
A.M. Sintes, A.A. Coley, D.J. McManus
|
On space-times admitting shear-free, irrotational, geodesic null
congruences
|
Latex, 4 pages. Published in "Analytical and Numerical Approaches to
Relativity: Sources of Gravitational Radiation". Edts. C. Bona, J. Carot, L.
Mas and J. Stela; U.I.B. Mallorca, pp. 266-270 (1998)
| null | null | null |
gr-qc
| null |
Space-times admitting a shear-free, irrotational, geodesic null congruence
are studied. Attention is focused on those space-times in which the
gravitational field is a combination of a perfect fluid and null radiation.
|
[
{
"created": "Tue, 16 May 2000 13:56:42 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Sintes",
"A. M.",
""
],
[
"Coley",
"A. A.",
""
],
[
"McManus",
"D. J.",
""
]
] |
Space-times admitting a shear-free, irrotational, geodesic null congruence are studied. Attention is focused on those space-times in which the gravitational field is a combination of a perfect fluid and null radiation.
|
1703.08518
|
Youngsub Yoon
|
Youngsub Yoon
|
Maxwell-Boltzmann type Hawking radiation
|
4 pages, accepted for publication at Modern Physics Letters A
|
Mod. Phys. Lett. A, Vol. 32, No. 12 (2017) 1750071
|
10.1142/S0217732317500717
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Twenty years ago, Rovelli proposed that the degeneracy of black hole (i.e.
the exponential of the Bekenstein-Hawking entropy) is given by the number of
ways the black hole horizon area can be expressed as a sum of unit areas.
However, when counting the sum, one should treat the area quanta on the black
hole horizon as distinguishable. This distinguishability of area quanta is
noted in Rovelli's paper. Building on this idea, we derive that the Hawking
radiation spectrum is not given by Planck radiation spectrum (i.e.,
Bose-Einstein distribution) but given by Maxwell-Boltzmann distribution.
|
[
{
"created": "Thu, 23 Mar 2017 02:50:57 GMT",
"version": "v1"
}
] |
2017-04-05
|
[
[
"Yoon",
"Youngsub",
""
]
] |
Twenty years ago, Rovelli proposed that the degeneracy of black hole (i.e. the exponential of the Bekenstein-Hawking entropy) is given by the number of ways the black hole horizon area can be expressed as a sum of unit areas. However, when counting the sum, one should treat the area quanta on the black hole horizon as distinguishable. This distinguishability of area quanta is noted in Rovelli's paper. Building on this idea, we derive that the Hawking radiation spectrum is not given by Planck radiation spectrum (i.e., Bose-Einstein distribution) but given by Maxwell-Boltzmann distribution.
|
1407.5551
|
Hector Javier Hortua
|
Hector J. Hortua and Leonardo Casta\~neda
|
Equivalence between formulations in Cosmological Perturbation Theory:
The primordial magnetic fields as an example
|
Conference Proceedings, Magnetic Fields in the Universe IV, Playa del
Carmen, Mexico, February 2013
| null | null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Nowdays, Cosmological Perturbation Theory is a standard and useful tool in
theoretical cosmology. In this work, we compare the 1+3 covariant formalism in
perturbation theory (Ellis et al.) to the gauge invariant approach (Bruni et
al.), and we show the equivalence of these formalisms to fix the choice of the
perturbed variables (gauge choice) in magnetogenesis. We analyze the evolution
of primordial magnetic fields through perturbation theory and we discuss the
similarities and differences between these two approaches. We get the Maxwell's
equations and show a cosmic dynamo like equation written in Poisson gauge,
computing the evolution of primordial magnetic fields. Finally, prospects
around these formalisms in the study of magnetogenesis are discussed.
|
[
{
"created": "Mon, 21 Jul 2014 16:26:23 GMT",
"version": "v1"
}
] |
2014-07-22
|
[
[
"Hortua",
"Hector J.",
""
],
[
"Castañeda",
"Leonardo",
""
]
] |
Nowdays, Cosmological Perturbation Theory is a standard and useful tool in theoretical cosmology. In this work, we compare the 1+3 covariant formalism in perturbation theory (Ellis et al.) to the gauge invariant approach (Bruni et al.), and we show the equivalence of these formalisms to fix the choice of the perturbed variables (gauge choice) in magnetogenesis. We analyze the evolution of primordial magnetic fields through perturbation theory and we discuss the similarities and differences between these two approaches. We get the Maxwell's equations and show a cosmic dynamo like equation written in Poisson gauge, computing the evolution of primordial magnetic fields. Finally, prospects around these formalisms in the study of magnetogenesis are discussed.
|
2408.01871
|
Mohammed Khalil
|
Yilber Fabian Bautista, Mohammed Khalil, Matteo Sergola, Chris
Kavanagh, Justin Vines
|
Post-Newtonian observables for aligned-spin binaries to sixth order in
spin from gravitational self-force and Compton amplitudes
|
35 pages, 3 ancillary files
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Accurate modeling of compact binaries is essential for gravitational-wave
detection and parameter estimation, with spin being an important effect to
include in waveform models. In this paper, we derive new post-Newtonian (PN)
results for the conservative aligned-spin dynamics at next-to-next-to-leading
order for the spin$^3$ and spin$^4$ contributions, in addition to the
next-to-leading order (NLO) spin$^5$ and spin$^6$ contributions. One approach
we follow is the Tutti Frutti method, which relates PN and gravitational
self-force (GSF) results through the redshift and spin-precession invariants,
by making use of the simple dependence of the scattering angle on the symmetric
mass ratio. However, an ambiguity arises at the NLO spin$^5$ contribution, due
to transcendental functions of the Kerr spin in the redshift; this is also the
order at which Compton amplitudes calculations are affected by spurious poles.
Therefore, we follow an additional approach to determine the NLO spin$^5$ and
spin$^6$ dynamics: using on-shell Compton amplitudes obtained from black hole
perturbation theory. The Compton amplitude used in this work is composed of the
unambiguous tree-level far-zone part reported in [Phys. Rev. D 109, no.8,
084071 (2024)], as well as the full, non-interfering with the far-zone,
$\ell=2$ partial wave contributions from the near zone, which are responsible
for capturing Kerr finite-size effects. Other results in this paper include
deriving the scattering angle of a spinning test body in a Kerr background from
a parametrized worldline action, and computing the redshift and spin-precession
invariants for eccentric orbits without an eccentricity expansion.
|
[
{
"created": "Sat, 3 Aug 2024 22:33:01 GMT",
"version": "v1"
}
] |
2024-08-06
|
[
[
"Bautista",
"Yilber Fabian",
""
],
[
"Khalil",
"Mohammed",
""
],
[
"Sergola",
"Matteo",
""
],
[
"Kavanagh",
"Chris",
""
],
[
"Vines",
"Justin",
""
]
] |
Accurate modeling of compact binaries is essential for gravitational-wave detection and parameter estimation, with spin being an important effect to include in waveform models. In this paper, we derive new post-Newtonian (PN) results for the conservative aligned-spin dynamics at next-to-next-to-leading order for the spin$^3$ and spin$^4$ contributions, in addition to the next-to-leading order (NLO) spin$^5$ and spin$^6$ contributions. One approach we follow is the Tutti Frutti method, which relates PN and gravitational self-force (GSF) results through the redshift and spin-precession invariants, by making use of the simple dependence of the scattering angle on the symmetric mass ratio. However, an ambiguity arises at the NLO spin$^5$ contribution, due to transcendental functions of the Kerr spin in the redshift; this is also the order at which Compton amplitudes calculations are affected by spurious poles. Therefore, we follow an additional approach to determine the NLO spin$^5$ and spin$^6$ dynamics: using on-shell Compton amplitudes obtained from black hole perturbation theory. The Compton amplitude used in this work is composed of the unambiguous tree-level far-zone part reported in [Phys. Rev. D 109, no.8, 084071 (2024)], as well as the full, non-interfering with the far-zone, $\ell=2$ partial wave contributions from the near zone, which are responsible for capturing Kerr finite-size effects. Other results in this paper include deriving the scattering angle of a spinning test body in a Kerr background from a parametrized worldline action, and computing the redshift and spin-precession invariants for eccentric orbits without an eccentricity expansion.
|
gr-qc/0408064
|
David Garfinkle
|
David Garfinkle
|
Gravitational collapse in anti de Sitter space
|
9 pages, 13 figures
|
Phys.Rev. D70 (2004) 104015
|
10.1103/PhysRevD.70.104015
| null |
gr-qc
| null |
A numerical and analytic treatment is presented here of the evolution of
initial data of the kind that was conjectured by Hertog, Horowitz and Maeda to
lead to a violation of cosmic censorship. That initial data is essentially a
thick domain wall connecting two regions of anti de Sitter space. The evolution
results in no violation of cosmic censorship, but rather the formation of a
small black hole.
|
[
{
"created": "Wed, 18 Aug 2004 15:52:14 GMT",
"version": "v1"
}
] |
2009-11-10
|
[
[
"Garfinkle",
"David",
""
]
] |
A numerical and analytic treatment is presented here of the evolution of initial data of the kind that was conjectured by Hertog, Horowitz and Maeda to lead to a violation of cosmic censorship. That initial data is essentially a thick domain wall connecting two regions of anti de Sitter space. The evolution results in no violation of cosmic censorship, but rather the formation of a small black hole.
|
2407.17890
|
Pablo Ba\~n\'on P\'erez
|
Pablo Ba\~n\'on P\'erez and Maarten DeKieviet
|
Differential Forms vs Geometric Algebra: The quest for the best
geometric language
|
26 pages, 6 figures
| null | null | null |
gr-qc math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Differential forms is a highly geometric formalism for physics used from
field theories to General Relativity (GR) which has been a great upgrade over
vector calculus with the advantages of being coordinate-free and carrying a
high degree of geometrical content.
In recent years, Geometric Algebra appeared claiming to be a unifying
language for physics and mathematics with a high level of geometrical content.
Its strength is based on the unification of the inner and outer product into a
single geometric operation, and its easy interpretation.
Given their similarities, in this article we compare both formalisms
side-by-side to narrow the gap between them in literature. We present a direct
translation including differential identities, integration theorems and various
algebraic identities.
As an illustrative example, we present the case of classical electrodynamics
in both formalism and finish with their description of GR.
|
[
{
"created": "Thu, 25 Jul 2024 09:19:06 GMT",
"version": "v1"
}
] |
2024-07-26
|
[
[
"Pérez",
"Pablo Bañón",
""
],
[
"DeKieviet",
"Maarten",
""
]
] |
Differential forms is a highly geometric formalism for physics used from field theories to General Relativity (GR) which has been a great upgrade over vector calculus with the advantages of being coordinate-free and carrying a high degree of geometrical content. In recent years, Geometric Algebra appeared claiming to be a unifying language for physics and mathematics with a high level of geometrical content. Its strength is based on the unification of the inner and outer product into a single geometric operation, and its easy interpretation. Given their similarities, in this article we compare both formalisms side-by-side to narrow the gap between them in literature. We present a direct translation including differential identities, integration theorems and various algebraic identities. As an illustrative example, we present the case of classical electrodynamics in both formalism and finish with their description of GR.
|
gr-qc/0204021
|
Iver H{\aa}kon Brevik
|
I. Brevik
|
Cardy-Verlinde Entropy Formula in the Presence of a General Cosmological
State Equation
|
10 pages, LaTeX, no figures
|
Phys.Rev.D65:127302,2002
|
10.1103/PhysRevD.65.127302
| null |
gr-qc hep-th
| null |
As recently found by Youm [hep-th/0201268], the entropy of the universe will
no longer be expressible in the conventional Cardy-Verlinde form if one relaxes
the radiation dominance state equation and instead assumes a more general
equation of the form p=(\gamma-1)\rho, with \gamma a constant. We show that
Youm's generalized entropy formula remains valid when the cosmic fluid is no
longer ideal, but is allowed to possess a constant bulk viscosity \zeta. We
supply our analysis with some numerical estimates, thus calculating the scale
factor a(t) for a k=0 universe, and also calculate via a perturbative expansion
in \zeta the magnitude of the viscosity-induced correction to the scale factor
if the universe is radiation dominated.
|
[
{
"created": "Thu, 4 Apr 2002 15:07:26 GMT",
"version": "v1"
}
] |
2009-01-14
|
[
[
"Brevik",
"I.",
""
]
] |
As recently found by Youm [hep-th/0201268], the entropy of the universe will no longer be expressible in the conventional Cardy-Verlinde form if one relaxes the radiation dominance state equation and instead assumes a more general equation of the form p=(\gamma-1)\rho, with \gamma a constant. We show that Youm's generalized entropy formula remains valid when the cosmic fluid is no longer ideal, but is allowed to possess a constant bulk viscosity \zeta. We supply our analysis with some numerical estimates, thus calculating the scale factor a(t) for a k=0 universe, and also calculate via a perturbative expansion in \zeta the magnitude of the viscosity-induced correction to the scale factor if the universe is radiation dominated.
|
gr-qc/9807017
|
Steven R. Brandt
|
S. Brandt, J.A. Font, J.M. Ibanez, J. Masso and E. Seidel
|
Numerical evolution of matter in dynamical axisymmetric black hole
spacetimes. I. Methods and tests
|
42 pages, 20 figures, submitted to Phys Rev D
|
Comput.Phys.Commun. 124 (2000) 169-196
|
10.1016/S0010-4655(99)00447-6
| null |
gr-qc astro-ph
| null |
We have developed a numerical code to study the evolution of self-gravitating
matter in dynamic black hole axisymmetric spacetimes in general relativity. The
matter fields are evolved with a high-resolution shock-capturing scheme that
uses the characteristic information of the general relativistic hydrodynamic
equations to build up a linearized Riemann solver. The spacetime is evolved
with an axisymmetric ADM code designed to evolve a wormhole in full general
relativity. We discuss the numerical and algorithmic issues related to the
effective coupling of the hydrodynamical and spacetime pieces of the code, as
well as the numerical methods and gauge conditions we use to evolve such
spacetimes. The code has been put through a series of tests that verify that it
functions correctly. Particularly, we develop and describe a new set of testbed
calculations and techniques designed to handle dynamically sliced,
self-gravitating matter flows on black holes, and subject the code to these
tests. We make some studies of the spherical and axisymmetric accretion onto a
dynamic black hole, the fully dynamical evolution of imploding shells of dust
with a black hole, the evolution of matter in rotating spacetimes, the
gravitational radiation induced by the presence of the matter fields and the
behavior of apparent horizons through the evolution.
|
[
{
"created": "Thu, 9 Jul 1998 09:09:20 GMT",
"version": "v1"
}
] |
2009-10-31
|
[
[
"Brandt",
"S.",
""
],
[
"Font",
"J. A.",
""
],
[
"Ibanez",
"J. M.",
""
],
[
"Masso",
"J.",
""
],
[
"Seidel",
"E.",
""
]
] |
We have developed a numerical code to study the evolution of self-gravitating matter in dynamic black hole axisymmetric spacetimes in general relativity. The matter fields are evolved with a high-resolution shock-capturing scheme that uses the characteristic information of the general relativistic hydrodynamic equations to build up a linearized Riemann solver. The spacetime is evolved with an axisymmetric ADM code designed to evolve a wormhole in full general relativity. We discuss the numerical and algorithmic issues related to the effective coupling of the hydrodynamical and spacetime pieces of the code, as well as the numerical methods and gauge conditions we use to evolve such spacetimes. The code has been put through a series of tests that verify that it functions correctly. Particularly, we develop and describe a new set of testbed calculations and techniques designed to handle dynamically sliced, self-gravitating matter flows on black holes, and subject the code to these tests. We make some studies of the spherical and axisymmetric accretion onto a dynamic black hole, the fully dynamical evolution of imploding shells of dust with a black hole, the evolution of matter in rotating spacetimes, the gravitational radiation induced by the presence of the matter fields and the behavior of apparent horizons through the evolution.
|
1411.1691
|
Pierre-Andr\'e Mandrin Ph.D.
|
Pierre-Andr\'e Mandrin
|
Particle interactions predicted from minimum information
|
8 pages. Improved: v2: quantum numbers, symmetries, indices. v3:
Proof altern. based on GR + phase invar.; quantum term removed; conserved
quantities / indices; space-time symm.; all fermions (SM); boson chains;
shortened. v4; Full space-time symm.; flavours U(1)xSU(2); Spin 1/2
torsion-compatible. v5: minor changes: fermion multiplicity; fermion indices,
alpha^mu. Submitted for publication
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
A systematic structure of particle interactions is predicted within and
beyond the standard model. The proof is performed either on the basis of (A) a
generalisable form of general relativity or, equivalently, (B) minimum
information quantum gravity. The emerging structure comprises several chains of
interaction generations, one generation being partly realised by the
electroweak and the strong interaction. Further interactions have not yet been
observed but could be observable in high energy particle collision experiments
in the future.
|
[
{
"created": "Thu, 6 Nov 2014 18:36:46 GMT",
"version": "v1"
},
{
"created": "Mon, 17 Nov 2014 20:27:26 GMT",
"version": "v2"
},
{
"created": "Sat, 27 Dec 2014 16:46:03 GMT",
"version": "v3"
},
{
"created": "Fri, 2 Jan 2015 21:26:32 GMT",
"version": "v4"
},
{
"created": "Mon, 19 Jan 2015 15:20:57 GMT",
"version": "v5"
}
] |
2016-02-22
|
[
[
"Mandrin",
"Pierre-André",
""
]
] |
A systematic structure of particle interactions is predicted within and beyond the standard model. The proof is performed either on the basis of (A) a generalisable form of general relativity or, equivalently, (B) minimum information quantum gravity. The emerging structure comprises several chains of interaction generations, one generation being partly realised by the electroweak and the strong interaction. Further interactions have not yet been observed but could be observable in high energy particle collision experiments in the future.
|
1902.05202
|
Gregory Eskin
|
Gregory Eskin
|
Hawking radiation from not-extremal and extremal Reissner-Nordstrom
black holes
| null |
Pure and Applied Functional Analysis, 2 (2022), no. 3, 975-992
| null | null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We consider the non-extremal Reissner-Nordstrom black hole and construct a
wave packet that exhibits the Hawking radiation. We find the average of the
number of the created particles with respect to the $|0\rangle$ vacuum state
and with respect to Unruh type vacuum state. The average of the number operator
in the $|0\rangle$ vacuum state consists of two terms: one is related to the
Hawking radiation and the second is not related. We use the same construction
for the extremal RN black hole and get that the average of the number operator
with respect to the $|0\rangle$ vacuum state is also a sum of two term, where
the one related to the Hawking radiation is equal to zero. This result is
consistent with other works on the Hawking radiation for the extremal RN black
hole.
|
[
{
"created": "Thu, 14 Feb 2019 03:19:37 GMT",
"version": "v1"
},
{
"created": "Sun, 11 Aug 2019 05:38:21 GMT",
"version": "v2"
},
{
"created": "Tue, 8 Sep 2020 22:16:55 GMT",
"version": "v3"
}
] |
2023-03-27
|
[
[
"Eskin",
"Gregory",
""
]
] |
We consider the non-extremal Reissner-Nordstrom black hole and construct a wave packet that exhibits the Hawking radiation. We find the average of the number of the created particles with respect to the $|0\rangle$ vacuum state and with respect to Unruh type vacuum state. The average of the number operator in the $|0\rangle$ vacuum state consists of two terms: one is related to the Hawking radiation and the second is not related. We use the same construction for the extremal RN black hole and get that the average of the number operator with respect to the $|0\rangle$ vacuum state is also a sum of two term, where the one related to the Hawking radiation is equal to zero. This result is consistent with other works on the Hawking radiation for the extremal RN black hole.
|
1101.3662
|
J. Fernando Barbero G.
|
J. Fernando Barbero G., Eduardo J. S. Villase\~nor
|
Statistical description of the black hole degeneracy spectrum
|
41 pages, 12 figures
|
Phys.Rev.D83:104013,2011
|
10.1103/PhysRevD.83.104013
| null |
gr-qc hep-th math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We use mathematical methods based on generating functions to study the
statistical properties of the black hole degeneracy spectrum in loop quantum
gravity. In particular we will study the persistence of the observed effective
quantization of the entropy as a function of the horizon area. We will show
that this quantization disappears as the area increases despite the existence
of black hole configurations with a large degeneracy. The methods that we
describe here can be adapted to the study of the statistical properties of the
black hole degeneracy spectrum for all the existing proposals to define black
hole entropy in loop quantum gravity.
|
[
{
"created": "Wed, 19 Jan 2011 10:57:30 GMT",
"version": "v1"
}
] |
2015-03-17
|
[
[
"G.",
"J. Fernando Barbero",
""
],
[
"Villaseñor",
"Eduardo J. S.",
""
]
] |
We use mathematical methods based on generating functions to study the statistical properties of the black hole degeneracy spectrum in loop quantum gravity. In particular we will study the persistence of the observed effective quantization of the entropy as a function of the horizon area. We will show that this quantization disappears as the area increases despite the existence of black hole configurations with a large degeneracy. The methods that we describe here can be adapted to the study of the statistical properties of the black hole degeneracy spectrum for all the existing proposals to define black hole entropy in loop quantum gravity.
|
gr-qc/0610003
|
Kirill Bronnikov
|
K.A. Bronnikov, R.V. Konoplich, S.G. Rubin
|
Diversity of universes created by pure gravity
|
14 pages, 8 figures, revtex4. Final version, some considerations
added in response to referee remarks
|
Class.Quant.Grav.24:1261-1278,2007
|
10.1088/0264-9381/24/5/011
| null |
gr-qc
| null |
We show that a number of problems of modern cosmology may be solved in the
framework of multidimensional gravity with high-order curvature invariants,
without invoking other fields. We use a method employing a slow-change
approximation, able to work with rather a general form of the gravitational
action, and consider Kaluza-Klein type space-times with one or several extra
factor spaces. A vast choice of effective theories suggested by the present
framework may be stressed: even if the initial Lagrangian is entirely fixed,
one obtains quite different models for different numbers, dimensions and
topologies of the extra factor spaces. As examples of problems addressed we
consider (i) explanation of the present accelerated expansion of the Universe,
with a reasonably small cosmological constant, and the problem of its fine
tuning is considered from a new point of view; (ii) the mechanism of closed
wall production in the early Universe; such walls are necessary for massive
primordial black hole formation which is an important stage in some scenarios
of cosmic structure formation; (iii) sufficient particle production rate at the
end of inflation; (iv) it is shown that our Universe may contain spatial
domains with a macroscopic size of extra dimensions. We also discuss chaotic
attractors appearing at possible nodes of the kinetic term of the effective
scalar field Lagrangian.
|
[
{
"created": "Sun, 1 Oct 2006 14:14:20 GMT",
"version": "v1"
},
{
"created": "Tue, 27 Feb 2007 21:16:41 GMT",
"version": "v2"
}
] |
2008-11-26
|
[
[
"Bronnikov",
"K. A.",
""
],
[
"Konoplich",
"R. V.",
""
],
[
"Rubin",
"S. G.",
""
]
] |
We show that a number of problems of modern cosmology may be solved in the framework of multidimensional gravity with high-order curvature invariants, without invoking other fields. We use a method employing a slow-change approximation, able to work with rather a general form of the gravitational action, and consider Kaluza-Klein type space-times with one or several extra factor spaces. A vast choice of effective theories suggested by the present framework may be stressed: even if the initial Lagrangian is entirely fixed, one obtains quite different models for different numbers, dimensions and topologies of the extra factor spaces. As examples of problems addressed we consider (i) explanation of the present accelerated expansion of the Universe, with a reasonably small cosmological constant, and the problem of its fine tuning is considered from a new point of view; (ii) the mechanism of closed wall production in the early Universe; such walls are necessary for massive primordial black hole formation which is an important stage in some scenarios of cosmic structure formation; (iii) sufficient particle production rate at the end of inflation; (iv) it is shown that our Universe may contain spatial domains with a macroscopic size of extra dimensions. We also discuss chaotic attractors appearing at possible nodes of the kinetic term of the effective scalar field Lagrangian.
|
gr-qc/9806026
|
Rainer Kuehne
|
Rainer W. Kuhne
|
Gauge Theory of Gravity Requires Massive Torsion Field
|
3 pages, Revtex
|
Int.J.Mod.Phys.A14:2531-2536,1999
|
10.1142/S0217751X99001251
| null |
gr-qc hep-ph hep-th
| null |
One of the greatest unsolved issues of the physics of this century is to find
a quantum field theory of gravity. According to a vast amount of literature
unification of quantum field theory and gravitation requires a gauge theory of
gravity which includes torsion and an associated spin field. Various models
including either massive or massless torsion fields have been suggested. We
present arguments for a massive torsion field, where the probable rest mass of
the corresponding spin three gauge boson is the Planck mass.
|
[
{
"created": "Thu, 4 Jun 1998 17:23:06 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Kuhne",
"Rainer W.",
""
]
] |
One of the greatest unsolved issues of the physics of this century is to find a quantum field theory of gravity. According to a vast amount of literature unification of quantum field theory and gravitation requires a gauge theory of gravity which includes torsion and an associated spin field. Various models including either massive or massless torsion fields have been suggested. We present arguments for a massive torsion field, where the probable rest mass of the corresponding spin three gauge boson is the Planck mass.
|
gr-qc/0411014
|
Sbp Wickramasuriya
|
S.B.P. Wickramasuriya, V. Joseph, and K.I.S. Karunaratne
|
Geodesics in a Toroidal space-time
|
10 Pages
| null | null | null |
gr-qc
| null |
We take a three dimensional Euclidian metric in toroidal coordinates and
consider the corresponding Laplace equation. The simplest solution of this
equation is taken. Based on this we build a Weyl space-time. This space-time is
transformed to cylindrical coordinates. It is shown by using Mathematica that
Weyl equations in cylindrical coordinates are satisfied. Geodesic motion is
considered along the symmetric axis as well as along the radii of the
singularity, which is the cause of the space time.
|
[
{
"created": "Tue, 2 Nov 2004 02:43:33 GMT",
"version": "v1"
},
{
"created": "Mon, 29 Nov 2004 03:53:25 GMT",
"version": "v2"
}
] |
2007-05-23
|
[
[
"Wickramasuriya",
"S. B. P.",
""
],
[
"Joseph",
"V.",
""
],
[
"Karunaratne",
"K. I. S.",
""
]
] |
We take a three dimensional Euclidian metric in toroidal coordinates and consider the corresponding Laplace equation. The simplest solution of this equation is taken. Based on this we build a Weyl space-time. This space-time is transformed to cylindrical coordinates. It is shown by using Mathematica that Weyl equations in cylindrical coordinates are satisfied. Geodesic motion is considered along the symmetric axis as well as along the radii of the singularity, which is the cause of the space time.
|
1910.03378
|
Zhen-Ming Xu
|
Zhen-Ming Xu, Bin Wu and Wen-Li Yang
|
Fine micro-thermal structures for Reissner-Nordstr\"om black hole
|
v1:5 pages, 1 figure;v2:clarifications and references added; v3:
final version to be published in Chinese Physics C
|
Chinese Physics C Vol. 44, No. 9 (2020) 095106
|
10.1088/1674-1137/44/9/095106
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We solve the condundrum on whether the molecules of the Reissner-Nordstr\"om
black hole interact through the Ruppeiner thermodynamic geometry, basing our
study on the concept of the black hole molecule proposed in [Phys. Rev. Lett.
115 (2015) 111302] and choosing the appropriate extensive variables. Our
results show that the Reissner-Nordstr\"om black hole is indeed an interaction
system that may be dominated by repulsive interaction. More importantly, with
the help of a novel quantity, namely the thermal-charge density, we describe
the fine micro-thermal structures of the Reissner-Nordstr\"om black hole in
detail. Three different phases are presented, namely the free, interactive, and
balanced phases. The thermal-charge density plays a role similar to the order
parameter, and the back hole undergoes a new phase transition between the free
phase and interactive phase. The competition between the free phase and
interactive phase exists, which leads to extreme behavior of the temperature of
the Reissner-Nordstr\"om black hole. For the extreme Reissner-Nordstr\"om black
hole, the entire system is completely in the interactive phase. More
importantly, we provide the thermodynamic micro-mechanism for the formation of
the naked singularity of the Reissner-Nordstr\"om black hole.
|
[
{
"created": "Tue, 8 Oct 2019 13:13:02 GMT",
"version": "v1"
},
{
"created": "Tue, 25 Feb 2020 05:10:36 GMT",
"version": "v2"
},
{
"created": "Wed, 6 May 2020 01:52:38 GMT",
"version": "v3"
},
{
"created": "Tue, 1 Sep 2020 08:38:42 GMT",
"version": "v4"
}
] |
2020-09-02
|
[
[
"Xu",
"Zhen-Ming",
""
],
[
"Wu",
"Bin",
""
],
[
"Yang",
"Wen-Li",
""
]
] |
We solve the condundrum on whether the molecules of the Reissner-Nordstr\"om black hole interact through the Ruppeiner thermodynamic geometry, basing our study on the concept of the black hole molecule proposed in [Phys. Rev. Lett. 115 (2015) 111302] and choosing the appropriate extensive variables. Our results show that the Reissner-Nordstr\"om black hole is indeed an interaction system that may be dominated by repulsive interaction. More importantly, with the help of a novel quantity, namely the thermal-charge density, we describe the fine micro-thermal structures of the Reissner-Nordstr\"om black hole in detail. Three different phases are presented, namely the free, interactive, and balanced phases. The thermal-charge density plays a role similar to the order parameter, and the back hole undergoes a new phase transition between the free phase and interactive phase. The competition between the free phase and interactive phase exists, which leads to extreme behavior of the temperature of the Reissner-Nordstr\"om black hole. For the extreme Reissner-Nordstr\"om black hole, the entire system is completely in the interactive phase. More importantly, we provide the thermodynamic micro-mechanism for the formation of the naked singularity of the Reissner-Nordstr\"om black hole.
|
1306.4011
|
Delsate T\'erence
|
Y. Brihaye and T. Delsate
|
Gravitating Q-tubes and cylindrical spacetime
|
14 pages, 7 figures. results extended, references added
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We consider a model involving a self-interacting complex scalar field
minimally coupled to gravity and emphasize the cylindrically symmetric
classical solutions. A general ansatz is performed which transforms the field
equations into a system of differential equations. In the generic case, the
scalar field depends on the four space-time coordinates. The underlying
Einstein vacuum equations are worth studying by themselve and lead to numerous
analytic results extending the Kasner solutions. The solutions of the coupled
system are -static as well as stationnary- gravitating Q-tubes of scalar matter
which deform space-time.
|
[
{
"created": "Mon, 17 Jun 2013 20:32:31 GMT",
"version": "v1"
},
{
"created": "Wed, 10 Jul 2013 08:40:38 GMT",
"version": "v2"
}
] |
2013-07-11
|
[
[
"Brihaye",
"Y.",
""
],
[
"Delsate",
"T.",
""
]
] |
We consider a model involving a self-interacting complex scalar field minimally coupled to gravity and emphasize the cylindrically symmetric classical solutions. A general ansatz is performed which transforms the field equations into a system of differential equations. In the generic case, the scalar field depends on the four space-time coordinates. The underlying Einstein vacuum equations are worth studying by themselve and lead to numerous analytic results extending the Kasner solutions. The solutions of the coupled system are -static as well as stationnary- gravitating Q-tubes of scalar matter which deform space-time.
|
gr-qc/9611020
|
Alberto Saa
|
Alberto Saa
|
Quantum dynamics of non-relativistic particles and isometric embeddings
|
Revtex, 14 pages
|
Class.Quant.Grav. 14 (1997) 385-390
|
10.1088/0264-9381/14/2/012
| null |
gr-qc
| null |
It is considered, in the framework of constrained systems, the quantum
dynamics of non-relativistic particles moving on a d-dimensional Riemannian
manifold M isometrically embedded in $R^{d+n}$. This generalizes recent
investigations where M has been assumed to be a hypersurface of $R^{d+1}$. We
show, contrary to recent claims, that constrained systems theory does not
contribute to the elimination of the ambiguities present in the canonical and
path integral formulations of the problem. These discrepancies with recent
works are discussed.
|
[
{
"created": "Fri, 8 Nov 1996 14:44:17 GMT",
"version": "v1"
}
] |
2009-10-28
|
[
[
"Saa",
"Alberto",
""
]
] |
It is considered, in the framework of constrained systems, the quantum dynamics of non-relativistic particles moving on a d-dimensional Riemannian manifold M isometrically embedded in $R^{d+n}$. This generalizes recent investigations where M has been assumed to be a hypersurface of $R^{d+1}$. We show, contrary to recent claims, that constrained systems theory does not contribute to the elimination of the ambiguities present in the canonical and path integral formulations of the problem. These discrepancies with recent works are discussed.
|
gr-qc/0602041
|
Dragan Hajdukovic
|
Dragan Slavkov Hajdukovic
|
Testing existence of antigravity
| null | null | null | null |
gr-qc
| null |
After a brief review of arguments in favor of antigravity (as gravitational
repulsion between matter and antimatter) we present a simple idea for an
experimental test using antiprotons. Different experimental realizations of the
same basic idea are considered
|
[
{
"created": "Sun, 12 Feb 2006 14:39:21 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Hajdukovic",
"Dragan Slavkov",
""
]
] |
After a brief review of arguments in favor of antigravity (as gravitational repulsion between matter and antimatter) we present a simple idea for an experimental test using antiprotons. Different experimental realizations of the same basic idea are considered
|
2305.06504
|
Denitsa Staicova
|
Denitsa Staicova
|
Impact of Cosmology on Lorentz Invariance Violation Constraints from GRB
Time-Delays
|
21 pages, prepared for the Classical and Quantum Gravity focus issue
"Focus on Quantum Gravity Phenomenology in the Multi-Messenger Era:
Challenges and Perspectives", final accepted for publication version
|
Class. Quantum Grav. 40 195012, 2023
|
10.1088/1361-6382/acf270
| null |
gr-qc astro-ph.CO astro-ph.HE
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Putting constraints on a possible Lorentz Invariance Violation (LIV) from
astrophysical sources such as gamma-ray bursts (GRBs) is essential for finding
evidences of new theories of quantum gravity (QG) that predict an
energy-dependent speed of light. This search has its own difficulties, so
usually, the effect of the cosmological model is understudied, with the default
model being a fixed-parameters $\Lambda$CDM. In this work, we use various
astrophysical datasets to study the effect of a number of dark energy models on
LIV constraints. To this end, we combine two public time-delay GRB datasets
with the supernovae Pantheon dataset, several measurements of angular baryonic
acoustic oscillations (BAO), the cosmic microwave background (CMB) distance
prior and an optional GRB or quasars dataset. For the LIV parameter $\alpha$,
we find the expected from previous works average value of $\alpha \sim 4 \times
10^{-4}$, corresponding to $E_{QG}\ge 10^{17}$ GeV for both time-delay (TD)
datasets, with the second one being more sensitive to the cosmological model.
The cosmology results in a minimum 20\% deviation in our constraints on the
energy. Interestingly, adding the TD points makes the DE models less-preferable
statistically and shifts the value of the parameter $c/(H_0 r_d)$ down, making
it smaller than the expected value. We observe that possible LIV measurements
critically depend on the transparency of the assumptions behind the published
data concerning cosmology, and taking this into account may be an important
contribution in the case of possible detection.
|
[
{
"created": "Thu, 11 May 2023 01:03:27 GMT",
"version": "v1"
},
{
"created": "Thu, 28 Sep 2023 23:16:55 GMT",
"version": "v2"
}
] |
2023-10-02
|
[
[
"Staicova",
"Denitsa",
""
]
] |
Putting constraints on a possible Lorentz Invariance Violation (LIV) from astrophysical sources such as gamma-ray bursts (GRBs) is essential for finding evidences of new theories of quantum gravity (QG) that predict an energy-dependent speed of light. This search has its own difficulties, so usually, the effect of the cosmological model is understudied, with the default model being a fixed-parameters $\Lambda$CDM. In this work, we use various astrophysical datasets to study the effect of a number of dark energy models on LIV constraints. To this end, we combine two public time-delay GRB datasets with the supernovae Pantheon dataset, several measurements of angular baryonic acoustic oscillations (BAO), the cosmic microwave background (CMB) distance prior and an optional GRB or quasars dataset. For the LIV parameter $\alpha$, we find the expected from previous works average value of $\alpha \sim 4 \times 10^{-4}$, corresponding to $E_{QG}\ge 10^{17}$ GeV for both time-delay (TD) datasets, with the second one being more sensitive to the cosmological model. The cosmology results in a minimum 20\% deviation in our constraints on the energy. Interestingly, adding the TD points makes the DE models less-preferable statistically and shifts the value of the parameter $c/(H_0 r_d)$ down, making it smaller than the expected value. We observe that possible LIV measurements critically depend on the transparency of the assumptions behind the published data concerning cosmology, and taking this into account may be an important contribution in the case of possible detection.
|
2006.07125
|
Erik Lentz
|
Erik W. Lentz
|
Breaking the Warp Barrier: Hyper-Fast Solitons in
Einstein-Maxwell-Plasma Theory
|
14 pages, 5 figures, comments welcome
| null | null | null |
gr-qc astro-ph.HE hep-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Solitons in space--time capable of transporting time-like observers at
superluminal speeds have long been tied to violations of the weak, strong, and
dominant energy conditions of general relativity. The negative-energy sources
required for these solitons must be created through energy-intensive
uncertainty principle processes as no such classical source is known in
particle physics. This paper overcomes this barrier by constructing a class of
soliton solutions that are capable of superluminal motion and sourced by purely
positive energy densities. The solitons are also shown to be capable of being
sourced from the stress-energy of a conducting plasma and classical
electromagnetic fields. This is the first example of hyper-fast solitons
resulting from known and familiar sources, reopening the discussion of
superluminal mechanisms rooted in conventional physics.
|
[
{
"created": "Fri, 12 Jun 2020 12:33:05 GMT",
"version": "v1"
},
{
"created": "Mon, 10 Aug 2020 14:55:58 GMT",
"version": "v2"
}
] |
2020-08-11
|
[
[
"Lentz",
"Erik W.",
""
]
] |
Solitons in space--time capable of transporting time-like observers at superluminal speeds have long been tied to violations of the weak, strong, and dominant energy conditions of general relativity. The negative-energy sources required for these solitons must be created through energy-intensive uncertainty principle processes as no such classical source is known in particle physics. This paper overcomes this barrier by constructing a class of soliton solutions that are capable of superluminal motion and sourced by purely positive energy densities. The solitons are also shown to be capable of being sourced from the stress-energy of a conducting plasma and classical electromagnetic fields. This is the first example of hyper-fast solitons resulting from known and familiar sources, reopening the discussion of superluminal mechanisms rooted in conventional physics.
|
2012.10025
|
Joshua Foo
|
Joshua Foo, Robert B. Mann and Magdalena Zych
|
Schr\"odinger's cat for de Sitter spacetime
|
15+3 pages, 10 figures. Accepted in CQG
|
Class. Quantum Grav. 38 115010 (2021)
|
10.1088/1361-6382/abf1c4
| null |
gr-qc hep-th quant-ph
|
http://creativecommons.org/licenses/by/4.0/
|
Quantum gravity is expected to contain descriptions of semiclassical
spacetime geometries in quantum superpositions. To date, no framework for
modelling such superpositions has been devised. Here, we provide a new
phenomenological description for the response of quantum probes (i.e.
Unruh-deWitt detectors) on a spacetime manifold in quantum superposition. By
introducing an additional control degree of freedom, one can assign a Hilbert
space to the spacetime, allowing it to exist in a superposition of spatial or
curvature states. Applying this approach to static de Sitter space, we discover
scenarios in which the effects produced by the quantum spacetime are
operationally indistinguishable from those induced by superpositions of Rindler
trajectories in Minkowski spacetime. The distinguishability of such quantum
spacetimes from superpositions of trajectories in flat space reduces to the
equivalence or non-equivalence of the field correlations between the superposed
amplitudes.
|
[
{
"created": "Fri, 18 Dec 2020 02:54:35 GMT",
"version": "v1"
},
{
"created": "Thu, 18 Mar 2021 02:10:57 GMT",
"version": "v2"
}
] |
2021-05-11
|
[
[
"Foo",
"Joshua",
""
],
[
"Mann",
"Robert B.",
""
],
[
"Zych",
"Magdalena",
""
]
] |
Quantum gravity is expected to contain descriptions of semiclassical spacetime geometries in quantum superpositions. To date, no framework for modelling such superpositions has been devised. Here, we provide a new phenomenological description for the response of quantum probes (i.e. Unruh-deWitt detectors) on a spacetime manifold in quantum superposition. By introducing an additional control degree of freedom, one can assign a Hilbert space to the spacetime, allowing it to exist in a superposition of spatial or curvature states. Applying this approach to static de Sitter space, we discover scenarios in which the effects produced by the quantum spacetime are operationally indistinguishable from those induced by superpositions of Rindler trajectories in Minkowski spacetime. The distinguishability of such quantum spacetimes from superpositions of trajectories in flat space reduces to the equivalence or non-equivalence of the field correlations between the superposed amplitudes.
|
gr-qc/0004002
|
David Brown
|
David Brown
|
Gravitational Waves from the Dynamical Bar Instability in a Rapidly
Rotating Star
|
Expanded version to be published in Phys. Rev. D: 13 pages, REVTeX,
13 figures, 9 TeX input files
|
Phys.Rev.D62:084024,2000
|
10.1103/PhysRevD.62.084024
| null |
gr-qc astro-ph
| null |
A rapidly rotating, axisymmetric star can be dynamically unstable to an m=2
"bar" mode that transforms the star from a disk shape to an elongated bar. The
fate of such a bar-shaped star is uncertain. Some previous numerical studies
indicate that the bar is short lived, lasting for only a few bar-rotation
periods, while other studies suggest that the bar is relatively long lived.
This paper contains the results of a numerical simulation of a rapidly rotating
gamma=5/3 fluid star. The simulation shows that the bar shape is long lived:
once the bar is established, the star retains this shape for more than 10
bar-rotation periods, through the end of the simulation. The results are
consistent with the conjecture that a star will retain its bar shape
indefinitely on a dynamical time scale, as long as its rotation rate exceeds
the threshold for secular bar instability. The results are described in terms
of a low density neutron star, but can be scaled to represent, for example, a
burned-out stellar core that is prevented from complete collapse by centrifugal
forces. Estimates for the gravitational-wave signal indicate that a dynamically
unstable neutron star in our galaxy can be detected easily by the first
generation of ground based gravitational-wave detectors. The signal for an
unstable neutron star in the Virgo cluster might be seen by the planned
advanced detectors. The Newtonian/quadrupole approximation is used throughout
this work.
|
[
{
"created": "Sat, 1 Apr 2000 03:21:53 GMT",
"version": "v1"
},
{
"created": "Tue, 11 Jul 2000 20:27:53 GMT",
"version": "v2"
}
] |
2010-11-19
|
[
[
"Brown",
"David",
""
]
] |
A rapidly rotating, axisymmetric star can be dynamically unstable to an m=2 "bar" mode that transforms the star from a disk shape to an elongated bar. The fate of such a bar-shaped star is uncertain. Some previous numerical studies indicate that the bar is short lived, lasting for only a few bar-rotation periods, while other studies suggest that the bar is relatively long lived. This paper contains the results of a numerical simulation of a rapidly rotating gamma=5/3 fluid star. The simulation shows that the bar shape is long lived: once the bar is established, the star retains this shape for more than 10 bar-rotation periods, through the end of the simulation. The results are consistent with the conjecture that a star will retain its bar shape indefinitely on a dynamical time scale, as long as its rotation rate exceeds the threshold for secular bar instability. The results are described in terms of a low density neutron star, but can be scaled to represent, for example, a burned-out stellar core that is prevented from complete collapse by centrifugal forces. Estimates for the gravitational-wave signal indicate that a dynamically unstable neutron star in our galaxy can be detected easily by the first generation of ground based gravitational-wave detectors. The signal for an unstable neutron star in the Virgo cluster might be seen by the planned advanced detectors. The Newtonian/quadrupole approximation is used throughout this work.
|
gr-qc/9411034
|
Neil Cornish
|
Neil J. Cornish and Janna J. Levin
|
Remarks about Static Back-Reaction on Black Hole Spacetimes
|
7 pages, LaTeX, one figure appended as a uuencoded and compressed
postscript file
| null | null |
UTPT-94-29, CITA-94-47
|
gr-qc
| null |
Recently, it has been claimed that the back reaction of vacuum polarization
on a black hole spacetime naturally regularizes infinities in the black hole
entropy. We examine the back reaction calculation and find no such
short-distance cut-off,in contradiction with these recent claims. Moreover, the
intuitive expectation that the perturbative calculation breaks down near the
event horizon is confirmed. The new surface gravity diverges and the metric is
degenerate at the stretched horizon.
|
[
{
"created": "Sun, 13 Nov 1994 23:12:14 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Cornish",
"Neil J.",
""
],
[
"Levin",
"Janna J.",
""
]
] |
Recently, it has been claimed that the back reaction of vacuum polarization on a black hole spacetime naturally regularizes infinities in the black hole entropy. We examine the back reaction calculation and find no such short-distance cut-off,in contradiction with these recent claims. Moreover, the intuitive expectation that the perturbative calculation breaks down near the event horizon is confirmed. The new surface gravity diverges and the metric is degenerate at the stretched horizon.
|
1607.03784
|
Jorge P\'aramos
|
Riccardo March, Jorge P\'aramos, Orfeu Bertolami, Simone Dell'Agnello
|
The 1/c expansion of nonminimally coupled curvature-matter gravity model
and constraints from planetary precession
|
21 pages, 7 figures
|
Phys. Rev. D 95, 024017 (2017)
|
10.1103/PhysRevD.95.024017
| null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The effects of a nonminimally coupled curvature-matter model of gravity on a
perturbed Minkowski metric are presented. The action functional of the model
involves two functions $f^1(R)$ and $f^2(R)$ of the Ricci scalar curvature $R$.
This work expands upon previous results, extending the framework developed
there to compute corrections up to order $O(1/c^4)$ of the $00$ component of
the metric tensor. It is shown that additional contributions arise due to both
the non-linear form $f^1(R)$ and the nonminimal coupling $f^2(R)$, including
exponential contributions that cannot be expressed as an expansion in powers of
$1/r$. Some possible experimental implications are assessed with application to
perihelion precession.
|
[
{
"created": "Thu, 7 Jul 2016 13:35:46 GMT",
"version": "v1"
}
] |
2017-01-18
|
[
[
"March",
"Riccardo",
""
],
[
"Páramos",
"Jorge",
""
],
[
"Bertolami",
"Orfeu",
""
],
[
"Dell'Agnello",
"Simone",
""
]
] |
The effects of a nonminimally coupled curvature-matter model of gravity on a perturbed Minkowski metric are presented. The action functional of the model involves two functions $f^1(R)$ and $f^2(R)$ of the Ricci scalar curvature $R$. This work expands upon previous results, extending the framework developed there to compute corrections up to order $O(1/c^4)$ of the $00$ component of the metric tensor. It is shown that additional contributions arise due to both the non-linear form $f^1(R)$ and the nonminimal coupling $f^2(R)$, including exponential contributions that cannot be expressed as an expansion in powers of $1/r$. Some possible experimental implications are assessed with application to perihelion precession.
|
gr-qc/0105040
|
Leor Barack
|
Leor Barack
|
Gravitational self force by mode sum regularization
|
Latex, 19 pages, accepted for publication in PRD
|
Phys.Rev. D64 (2001) 084021
|
10.1103/PhysRevD.64.084021
| null |
gr-qc
| null |
We propose a practical scheme for calculating the local gravitational
self-force experienced by a test mass particle moving in a black hole
spacetime. The method---equally effective for either weak or strong field
orbits---employs the {\em mode-sum regularization scheme} previously developed
for a scalar toy model. The starting point for the calculation, in this
approach, is the formal expression for the regularized self-force derived by
Mino et al. (and, independently, by Quinn and Wald), which involves a worldline
integral over the tail part of the retarded Green's function. This force is
decomposed into multipole (tensor harmonic) modes, whose sum is subjected to a
carefully designed regularization procedure. This procedure involves an
analytic derivation of certain ``regularization parameters'' by means of a
local analysis of the Green's function. This manuscript contains the following
main parts: (1) Introduction of the mode sum scheme as applied to the
gravitational case. (2) Two simple cases studied: the test case of a static
particle in flat spacetime, and the case of a particle at a turning point of a
radial geodesic in Schwarzschild spacetime. In both cases we derive all
necessary regularization parameters. (3) An Analytic foundation is set for
applying the scheme in more general cases. (In this paper, the mode sum scheme
is formulated within the harmonic gauge. The implementation of the scheme in
other gauges shall be discussed in a separate, forthcoming paper.)
|
[
{
"created": "Fri, 11 May 2001 15:03:20 GMT",
"version": "v1"
},
{
"created": "Mon, 13 Aug 2001 11:40:27 GMT",
"version": "v2"
}
] |
2009-11-07
|
[
[
"Barack",
"Leor",
""
]
] |
We propose a practical scheme for calculating the local gravitational self-force experienced by a test mass particle moving in a black hole spacetime. The method---equally effective for either weak or strong field orbits---employs the {\em mode-sum regularization scheme} previously developed for a scalar toy model. The starting point for the calculation, in this approach, is the formal expression for the regularized self-force derived by Mino et al. (and, independently, by Quinn and Wald), which involves a worldline integral over the tail part of the retarded Green's function. This force is decomposed into multipole (tensor harmonic) modes, whose sum is subjected to a carefully designed regularization procedure. This procedure involves an analytic derivation of certain ``regularization parameters'' by means of a local analysis of the Green's function. This manuscript contains the following main parts: (1) Introduction of the mode sum scheme as applied to the gravitational case. (2) Two simple cases studied: the test case of a static particle in flat spacetime, and the case of a particle at a turning point of a radial geodesic in Schwarzschild spacetime. In both cases we derive all necessary regularization parameters. (3) An Analytic foundation is set for applying the scheme in more general cases. (In this paper, the mode sum scheme is formulated within the harmonic gauge. The implementation of the scheme in other gauges shall be discussed in a separate, forthcoming paper.)
|
2011.13906
|
Thiago Guimar\~aes
|
T. M. Guimar\~aes, R. de C. Lima, S. H. Pereira
|
Cosmological inflation driven by a scalar torsion function
|
8 pages, 2 figures, submitted to EPJC
|
The European Physical Journal C (2021)
|
10.1140/epjc/s10052-021-09076-x
|
81, Article number: 271 (2021)
|
gr-qc
|
http://creativecommons.org/licenses/by-nc-nd/4.0/
|
A viable model for inflation driven by a torsion function in a Friedmann
background is presented. The scalar spectral index in the interval
$0.92\lesssim n_{s}\lesssim 0.97$ is obtained in order to satisfy the initial
conditions for inflation. The post inflationary phase is also studied, and the
analytical solutions obtained for scale factor and energy density generalizes
that ones for a matter dominated universe, indicating just a small deviation
from the standard model evolution. The same kind of torsion function used also
describes satisfactorily the recent acceleration of the universe, which could
indicate a possible unification of different phases, apart form specific
constants.
|
[
{
"created": "Fri, 27 Nov 2020 18:47:16 GMT",
"version": "v1"
}
] |
2022-09-22
|
[
[
"Guimarães",
"T. M.",
""
],
[
"Lima",
"R. de C.",
""
],
[
"Pereira",
"S. H.",
""
]
] |
A viable model for inflation driven by a torsion function in a Friedmann background is presented. The scalar spectral index in the interval $0.92\lesssim n_{s}\lesssim 0.97$ is obtained in order to satisfy the initial conditions for inflation. The post inflationary phase is also studied, and the analytical solutions obtained for scale factor and energy density generalizes that ones for a matter dominated universe, indicating just a small deviation from the standard model evolution. The same kind of torsion function used also describes satisfactorily the recent acceleration of the universe, which could indicate a possible unification of different phases, apart form specific constants.
|
0711.0612
|
Tolga Birkandan
|
T. Birkandan, M. Hortacsu
|
Singularity Structure and Stability Analysis of the Dirac Equation on
the Boundary of the Nutku Helicoid Solution
|
Version to appear in JMP
|
J.Math.Phys.49:054101,2008
|
10.1063/1.2913520
| null |
gr-qc math-ph math.MP
| null |
Dirac equation written on the boundary of the Nutku helicoid space consists
of a system of ordinary differential equations. We tried to analyze this system
and we found that it has a higher singularity than those of the Heun's
equations which give the solutions of the Dirac equation in the bulk. We also
lose an independent integral of motion on the boundary. This facts explain why
we could not find the solution of the system on the boundary in terms of known
functions. We make the stability analysis of the helicoid and catenoid cases
and end up with an appendix which gives a new example where one encounters a
form of the Heun equation.
|
[
{
"created": "Mon, 5 Nov 2007 11:23:08 GMT",
"version": "v1"
},
{
"created": "Mon, 19 Nov 2007 12:50:06 GMT",
"version": "v2"
},
{
"created": "Mon, 7 Apr 2008 06:57:44 GMT",
"version": "v3"
}
] |
2008-11-26
|
[
[
"Birkandan",
"T.",
""
],
[
"Hortacsu",
"M.",
""
]
] |
Dirac equation written on the boundary of the Nutku helicoid space consists of a system of ordinary differential equations. We tried to analyze this system and we found that it has a higher singularity than those of the Heun's equations which give the solutions of the Dirac equation in the bulk. We also lose an independent integral of motion on the boundary. This facts explain why we could not find the solution of the system on the boundary in terms of known functions. We make the stability analysis of the helicoid and catenoid cases and end up with an appendix which gives a new example where one encounters a form of the Heun equation.
|
gr-qc/0402088
|
Jean-Paul Mbelek
|
J.P. Mbelek
|
A scalar field modelling of the rotational curves of spiral galaxies
|
6 pages, poster presented at the symposium "The Dark Universe :
Matter, Energy, and Gravity", 2 - 5 April 2001, Space Telescope Science
Institute, Baltimore (USA, edited by M. Livio)
| null | null | null |
gr-qc astro-ph
| null |
In a previous work \cite{mbeleka}, we have modelled the rotation curves (RC)
of spiral galaxies by including in the equation of motion dynamical terms from
an external real self-interacting scalar field, $\phi$, minimally coupled to
gravity and which respects the equivalence principle in the absence of
electromagnetic fields. This model appears to have three free parameters : the
turnover radius, $r_{0}$, the maximum rotational velocity, $v_{max} =
v(r_{0})$, plus a strictly positive integer, $n$. Here, the coupling of the
$\phi$-field to other kinds of matter is emphasized at the expense of its
self-interaction. This reformulation presents the very advantageous possibility
that the same potential may be used now for all galaxies. New correlations are
established.
|
[
{
"created": "Fri, 20 Feb 2004 13:38:28 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Mbelek",
"J. P.",
""
]
] |
In a previous work \cite{mbeleka}, we have modelled the rotation curves (RC) of spiral galaxies by including in the equation of motion dynamical terms from an external real self-interacting scalar field, $\phi$, minimally coupled to gravity and which respects the equivalence principle in the absence of electromagnetic fields. This model appears to have three free parameters : the turnover radius, $r_{0}$, the maximum rotational velocity, $v_{max} = v(r_{0})$, plus a strictly positive integer, $n$. Here, the coupling of the $\phi$-field to other kinds of matter is emphasized at the expense of its self-interaction. This reformulation presents the very advantageous possibility that the same potential may be used now for all galaxies. New correlations are established.
|
2312.17335
|
Maulik K. Parikh
|
Maulik Parikh and Francesco Setti
|
Graviton Noise Correlation in Nearby Detectors
|
14 pages, 2 figures, LaTeX
| null | null | null |
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
We consider quantum gravity fluctuations in a pair of nearby gravitational
wave detectors. Quantum fluctuations of long-wavelength modes of the
gravitational field induce coherent fluctuations in the detectors, leading to
correlated noise. We determine the variance and covariance in the lengths of
the arms of the detectors, and thereby obtain the graviton noise correlation.
We find that the correlation depends on the angle between the detector arms as
well as their separation distance.
|
[
{
"created": "Thu, 28 Dec 2023 19:27:15 GMT",
"version": "v1"
}
] |
2024-01-01
|
[
[
"Parikh",
"Maulik",
""
],
[
"Setti",
"Francesco",
""
]
] |
We consider quantum gravity fluctuations in a pair of nearby gravitational wave detectors. Quantum fluctuations of long-wavelength modes of the gravitational field induce coherent fluctuations in the detectors, leading to correlated noise. We determine the variance and covariance in the lengths of the arms of the detectors, and thereby obtain the graviton noise correlation. We find that the correlation depends on the angle between the detector arms as well as their separation distance.
|
gr-qc/0610064
|
Hideyuki Tagoshi
|
TAMA Collaboration: T. Akutsu, et al
|
Results of the search for inspiraling compact star binaries from
TAMA300's observation in 2000-2004
|
8 pages, 4 Postscript figures, uses revtex4.sty The author list was
corrected
|
Phys.Rev.D74:122002,2006
|
10.1103/PhysRevD.74.122002
|
OU-TAP 271
|
gr-qc astro-ph
| null |
We analyze the data of TAMA300 detector to search for gravitational waves
from inspiraling compact star binaries with masses of the component stars in
the range 1-3Msolar. In this analysis, 2705 hours of data, taken during the
years 2000-2004, are used for the event search. We combine the results of
different observation runs, and obtained a single upper limit on the rate of
the coalescence of compact binaries in our Galaxy of 20 per year at a 90%
confidence level. In this upper limit, the effect of various systematic errors
such like the uncertainty of the background estimation and the calibration of
the detector's sensitivity are included.
|
[
{
"created": "Thu, 12 Oct 2006 09:29:56 GMT",
"version": "v1"
},
{
"created": "Mon, 16 Oct 2006 08:55:12 GMT",
"version": "v2"
}
] |
2008-11-26
|
[
[
"TAMA Collaboration",
"",
""
],
[
"Akutsu",
"T.",
""
]
] |
We analyze the data of TAMA300 detector to search for gravitational waves from inspiraling compact star binaries with masses of the component stars in the range 1-3Msolar. In this analysis, 2705 hours of data, taken during the years 2000-2004, are used for the event search. We combine the results of different observation runs, and obtained a single upper limit on the rate of the coalescence of compact binaries in our Galaxy of 20 per year at a 90% confidence level. In this upper limit, the effect of various systematic errors such like the uncertainty of the background estimation and the calibration of the detector's sensitivity are included.
|
1709.06058
|
Lukas Weih
|
Lukas R. Weih, Elias R. Most and Luciano Rezzolla
|
On the stability and maximum mass of differentially rotating
relativistic stars
|
5 pages, 7 figures, matches accepted version in MNRAS
|
Mon. Not. R. Astron. Soc., 473:L128-L130, 2018
|
10.1093/mnrasl/slx178
| null |
gr-qc astro-ph.HE
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The stability properties of rotating relativistic stars against prompt
gravitational collapse to a black hole are rather well understood for uniformly
rotating models. This is not the case for differentially rotating neutron
stars, which are expected to be produced in catastrophic events such as the
merger of binary system of neutron stars or the collapse of a massive stellar
core. We consider sequences of differentially rotating equilibrium models using
the $j$-constant law and by combining them with their dynamical evolution, we
show that a sufficient stability criterion for differentially rotating neutron
stars exists similar to the one of their uniformly rotating counterparts.
Namely: along a sequence of constant angular momentum, a dynamical instability
sets in for central rest-mass densities slightly below the one of the
equilibrium solution at the turning point. In addition, following Breu &
Rezzolla (2016), we show that "quasi-universal" relations can be found when
calculating the turning-point mass. In turn, this allows us to compute the
maximum mass allowed by differential rotation, $M_{\rm
max,dr}$, in terms of the maximum mass of the nonrotating configuration,
$M_{_{\rm TOV}}$, finding that $M_{\rm max, dr} \simeq \left(1.54 \pm
0.05\right) M_{_{\rm TOV}}$ for all the equations of state we have considered.
|
[
{
"created": "Mon, 18 Sep 2017 17:28:56 GMT",
"version": "v1"
},
{
"created": "Mon, 6 Nov 2017 12:03:56 GMT",
"version": "v2"
}
] |
2018-01-12
|
[
[
"Weih",
"Lukas R.",
""
],
[
"Most",
"Elias R.",
""
],
[
"Rezzolla",
"Luciano",
""
]
] |
The stability properties of rotating relativistic stars against prompt gravitational collapse to a black hole are rather well understood for uniformly rotating models. This is not the case for differentially rotating neutron stars, which are expected to be produced in catastrophic events such as the merger of binary system of neutron stars or the collapse of a massive stellar core. We consider sequences of differentially rotating equilibrium models using the $j$-constant law and by combining them with their dynamical evolution, we show that a sufficient stability criterion for differentially rotating neutron stars exists similar to the one of their uniformly rotating counterparts. Namely: along a sequence of constant angular momentum, a dynamical instability sets in for central rest-mass densities slightly below the one of the equilibrium solution at the turning point. In addition, following Breu & Rezzolla (2016), we show that "quasi-universal" relations can be found when calculating the turning-point mass. In turn, this allows us to compute the maximum mass allowed by differential rotation, $M_{\rm max,dr}$, in terms of the maximum mass of the nonrotating configuration, $M_{_{\rm TOV}}$, finding that $M_{\rm max, dr} \simeq \left(1.54 \pm 0.05\right) M_{_{\rm TOV}}$ for all the equations of state we have considered.
|
gr-qc/0101007
|
Kechkin O. V.
|
Alfredo Herrera-Aguilar, Oleg V. Kechkin
|
Bosonic string - Kaluza Klein theory exact solutions using 5D-6D
dualities
|
13 pages in LaTex
|
Mod.Phys.Lett. A16 (2001) 29-40
|
10.1142/S0217732301002857
| null |
gr-qc
| null |
We present the explicit formulae which allow to transform the general
solution of the 6D Kaluza--Klein theory on a 3--torus into the special solution
of the 6D bosonic string theory on a 3--torus as well as into the general
solution of the 5D bosonic string theory on a 2--torus. We construct a new
family of the extremal solutions of the 3D chiral equation for the
SL(4,R)/SO(4) coset matrix and interpret it in terms of the component fields of
these three duality related theories.
|
[
{
"created": "Sun, 31 Dec 2000 18:41:53 GMT",
"version": "v1"
}
] |
2009-11-07
|
[
[
"Herrera-Aguilar",
"Alfredo",
""
],
[
"Kechkin",
"Oleg V.",
""
]
] |
We present the explicit formulae which allow to transform the general solution of the 6D Kaluza--Klein theory on a 3--torus into the special solution of the 6D bosonic string theory on a 3--torus as well as into the general solution of the 5D bosonic string theory on a 2--torus. We construct a new family of the extremal solutions of the 3D chiral equation for the SL(4,R)/SO(4) coset matrix and interpret it in terms of the component fields of these three duality related theories.
|
2112.00091
|
Alexander Jercher
|
Alexander F. Jercher, Daniele Oriti, Andreas G. A. Pithis
|
Emergent Cosmology from Quantum Gravity in the Lorentzian Barrett-Crane
Tensorial Group Field Theory Model
|
37+16 pages, 1 figure
|
JCAP01(2022)050
|
10.1088/1475-7516/2022/01/050
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We study the cosmological sector of the Lorentzian Barrett-Crane (BC) model
coupled to a free massless scalar field in its Group Field Theory (GFT)
formulation, corresponding to the mean-field hydrodynamics obtained from
coherent condensate states. The relational evolution of the condensate with
respect to the scalar field yields effective dynamics of homogeneous and
isotropic cosmologies, similar to those previously obtained in
$\text{SU}(2)$-based EPRL-like models. Also in this manifestly Lorentzian
setting, in which only continuous $\text{SL}(2,\mathbb{C})$-representations are
used, we obtain generalized Friedmann equations that generically exhibit a
quantum bounce, and can reproduce all of the features of the cosmological
dynamics of EPRL-like models. This lends support to the expectation that the
EPRL-like and BC models may lie in the same continuum universality class, and
that the quantum gravity mechanism producing effective bouncing scenarios may
not depend directly on the discretization of geometric observables.
|
[
{
"created": "Tue, 30 Nov 2021 20:47:30 GMT",
"version": "v1"
},
{
"created": "Fri, 28 Jan 2022 10:08:02 GMT",
"version": "v2"
}
] |
2022-01-31
|
[
[
"Jercher",
"Alexander F.",
""
],
[
"Oriti",
"Daniele",
""
],
[
"Pithis",
"Andreas G. A.",
""
]
] |
We study the cosmological sector of the Lorentzian Barrett-Crane (BC) model coupled to a free massless scalar field in its Group Field Theory (GFT) formulation, corresponding to the mean-field hydrodynamics obtained from coherent condensate states. The relational evolution of the condensate with respect to the scalar field yields effective dynamics of homogeneous and isotropic cosmologies, similar to those previously obtained in $\text{SU}(2)$-based EPRL-like models. Also in this manifestly Lorentzian setting, in which only continuous $\text{SL}(2,\mathbb{C})$-representations are used, we obtain generalized Friedmann equations that generically exhibit a quantum bounce, and can reproduce all of the features of the cosmological dynamics of EPRL-like models. This lends support to the expectation that the EPRL-like and BC models may lie in the same continuum universality class, and that the quantum gravity mechanism producing effective bouncing scenarios may not depend directly on the discretization of geometric observables.
|
gr-qc/0503023
|
Yongge Ma
|
You Ding, Yongge Ma, Muxin Han, Jianbing Shao
|
Palatini Formalism of 5-Dimensional Kaluza-Klein Theory
|
10 pages
|
Mod.Phys.Lett. A20 (2005) 345-354
|
10.1142/S0217732305015689
| null |
gr-qc
| null |
The Einstein field equations can be derived in $n$ dimensions ($n>2$) by the
variations of the Palatini action. The Killing reduction of 5-dimensional
Palatini action is studied on the assumption that pentads and Lorentz
connections are preserved by the Killing vector field. A Palatini formalism of
4-dimensional action for gravity coupled to a vector field and a scalar field
is obtained, which gives exactly the same fields equations in Kaluza-Klein
theory.
|
[
{
"created": "Sat, 5 Mar 2005 04:02:41 GMT",
"version": "v1"
}
] |
2009-11-11
|
[
[
"Ding",
"You",
""
],
[
"Ma",
"Yongge",
""
],
[
"Han",
"Muxin",
""
],
[
"Shao",
"Jianbing",
""
]
] |
The Einstein field equations can be derived in $n$ dimensions ($n>2$) by the variations of the Palatini action. The Killing reduction of 5-dimensional Palatini action is studied on the assumption that pentads and Lorentz connections are preserved by the Killing vector field. A Palatini formalism of 4-dimensional action for gravity coupled to a vector field and a scalar field is obtained, which gives exactly the same fields equations in Kaluza-Klein theory.
|
2305.00459
|
Sattha Phalungsongsathit
|
Petarpa Boonserm, Sattha Phalungsongsathit, Kunlapat Sansuk, Pitayuth
Wongjun
|
Greybody factors for massive scalar field emitted from black holes in
dRGT massive gravity
|
22 pages, 19 figures
| null |
10.1140/epjc/s10052-023-11843-x
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Greybody factors are transmission probabilities of the Hawking radiation,
which are emitted from black holes and can be obtained from the gravitational
potential of black holes. The de Rham, Gabadadze, and Tolly (dRGT) massive
gravity is one of the gravity theories that modified general relativity. In
this paper, we investigate the greybody factor from the massive scalar field in
both the asymptotically dS and the AdS spacetime using the WKB and the rigorous
bound methods. We found that the greybody factor depends on the shape of the
potential as found in quantum mechanics. The higher the potential barrier, the
lower the amount of the grebody factor. Interestingly, for the low multipole
case, we found that there exists a critical mass which provides the maximum
bound of the greybody factor. This is a crucial feature of the massive scalar
field on the greybody factor from the black holes in both the asymptotically dS
and the AdS spacetime.
|
[
{
"created": "Sun, 30 Apr 2023 11:54:32 GMT",
"version": "v1"
}
] |
2023-08-09
|
[
[
"Boonserm",
"Petarpa",
""
],
[
"Phalungsongsathit",
"Sattha",
""
],
[
"Sansuk",
"Kunlapat",
""
],
[
"Wongjun",
"Pitayuth",
""
]
] |
Greybody factors are transmission probabilities of the Hawking radiation, which are emitted from black holes and can be obtained from the gravitational potential of black holes. The de Rham, Gabadadze, and Tolly (dRGT) massive gravity is one of the gravity theories that modified general relativity. In this paper, we investigate the greybody factor from the massive scalar field in both the asymptotically dS and the AdS spacetime using the WKB and the rigorous bound methods. We found that the greybody factor depends on the shape of the potential as found in quantum mechanics. The higher the potential barrier, the lower the amount of the grebody factor. Interestingly, for the low multipole case, we found that there exists a critical mass which provides the maximum bound of the greybody factor. This is a crucial feature of the massive scalar field on the greybody factor from the black holes in both the asymptotically dS and the AdS spacetime.
|
1712.00697
|
Jos\'e Fernando de Jesus
|
J. F. Jesus
|
Exact Solution for Flat Scale-Invariant Cosmology
|
Letter. 3 pages, 2 figures. Changed format for journal submission in
new version
| null | null | null |
gr-qc astro-ph.CO
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
An exact solution for the spatially flat scale-invariant Cosmology, recently
proposed by Maeder (2017) is deduced. No deviation from the numerical solution
was detected. The exact solution yields transparency for the dynamical
equations and faster cosmological constraints may be performed.
|
[
{
"created": "Sun, 3 Dec 2017 02:14:11 GMT",
"version": "v1"
},
{
"created": "Wed, 6 Dec 2017 13:12:46 GMT",
"version": "v2"
},
{
"created": "Mon, 26 Feb 2018 16:57:42 GMT",
"version": "v3"
}
] |
2018-02-27
|
[
[
"Jesus",
"J. F.",
""
]
] |
An exact solution for the spatially flat scale-invariant Cosmology, recently proposed by Maeder (2017) is deduced. No deviation from the numerical solution was detected. The exact solution yields transparency for the dynamical equations and faster cosmological constraints may be performed.
|
gr-qc/0012029
|
Fredrick A. Jenet
|
F. A. Jenet and T. A. Prince
|
Detection of variable frequency signals using a fast chirp transform
| null |
Phys.Rev.D62:122001,2000
|
10.1103/PhysRevD.62.122001
| null |
gr-qc
| null |
The detection of signals with varying frequency is important in many areas of
physics and astrophysics. The current work was motivated by a desire to detect
gravitational waves from the binary inspiral of neutron stars and black holes,
a topic of significant interest for the new generation of interferometric
gravitational wave detectors such as LIGO. However, this work has significant
generality beyond gravitational wave signal detection.
We define a Fast Chirp Transform (FCT) analogous to the Fast Fourier
Transform (FFT). Use of the FCT provides a simple and powerful formalism for
detection of signals with variable frequency just as Fourier transform
techniques provide a formalism for the detection of signals of constant
frequency. In particular, use of the FCT can alleviate the requirement of
generating complicated families of filter functions typically required in the
conventional matched filtering process. We briefly discuss the application of
the FCT to several signal detection problems of current interest.
|
[
{
"created": "Thu, 7 Dec 2000 07:35:45 GMT",
"version": "v1"
}
] |
2008-11-26
|
[
[
"Jenet",
"F. A.",
""
],
[
"Prince",
"T. A.",
""
]
] |
The detection of signals with varying frequency is important in many areas of physics and astrophysics. The current work was motivated by a desire to detect gravitational waves from the binary inspiral of neutron stars and black holes, a topic of significant interest for the new generation of interferometric gravitational wave detectors such as LIGO. However, this work has significant generality beyond gravitational wave signal detection. We define a Fast Chirp Transform (FCT) analogous to the Fast Fourier Transform (FFT). Use of the FCT provides a simple and powerful formalism for detection of signals with variable frequency just as Fourier transform techniques provide a formalism for the detection of signals of constant frequency. In particular, use of the FCT can alleviate the requirement of generating complicated families of filter functions typically required in the conventional matched filtering process. We briefly discuss the application of the FCT to several signal detection problems of current interest.
|
2311.12117
|
Matthew Mould
|
Matthew Mould, Christopher J. Moore, Davide Gerosa
|
Calibrating signal-to-noise ratio detection thresholds using
gravitational-wave catalogs
|
10 pages, 5 main figures (2 appendix figures)
|
Phys. Rev. D 109, 063013 (2024)
|
10.1103/PhysRevD.109.063013
| null |
gr-qc astro-ph.HE
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Searching for gravitational-wave signals is a challenging and computationally
intensive endeavor undertaken by multiple independent analysis pipelines. While
detection depends only on observed noisy data, it is sometimes inconsistently
defined in terms of source parameters that in reality are unknown, e.g., by
placing a threshold on the optimal signal-to-noise ratio (SNR). We present a
method to calibrate unphysical thresholds to search results by performing
Bayesian inference on real observations using a model that simultaneously
parametrizes the intrinsic network optimal SNR distribution and the effect of
search sensitivity on it. We find consistency with a fourth-order power law and
detection thresholds of $10.5_{-2.4}^{+2.1}$, $11.2_{-1.4}^{+1.2}$, and
$9.1_{-0.5}^{+0.5}$ (medians and $90\%$ credible intervals) for events with
false-alarm rates less than $1\,\mathrm{yr}^{-1}$ in the first, second, and
third LIGO-Virgo-KAGRA observing runs, respectively. Though event selection can
only be self-consistently reproduced by physical searches, employing our
inferred thresholds allows approximate observation-calibrated selection
criteria to be applied when efficiency is required and injection campaigns are
infeasible.
|
[
{
"created": "Mon, 20 Nov 2023 19:00:38 GMT",
"version": "v1"
},
{
"created": "Wed, 13 Mar 2024 21:17:13 GMT",
"version": "v2"
}
] |
2024-03-15
|
[
[
"Mould",
"Matthew",
""
],
[
"Moore",
"Christopher J.",
""
],
[
"Gerosa",
"Davide",
""
]
] |
Searching for gravitational-wave signals is a challenging and computationally intensive endeavor undertaken by multiple independent analysis pipelines. While detection depends only on observed noisy data, it is sometimes inconsistently defined in terms of source parameters that in reality are unknown, e.g., by placing a threshold on the optimal signal-to-noise ratio (SNR). We present a method to calibrate unphysical thresholds to search results by performing Bayesian inference on real observations using a model that simultaneously parametrizes the intrinsic network optimal SNR distribution and the effect of search sensitivity on it. We find consistency with a fourth-order power law and detection thresholds of $10.5_{-2.4}^{+2.1}$, $11.2_{-1.4}^{+1.2}$, and $9.1_{-0.5}^{+0.5}$ (medians and $90\%$ credible intervals) for events with false-alarm rates less than $1\,\mathrm{yr}^{-1}$ in the first, second, and third LIGO-Virgo-KAGRA observing runs, respectively. Though event selection can only be self-consistently reproduced by physical searches, employing our inferred thresholds allows approximate observation-calibrated selection criteria to be applied when efficiency is required and injection campaigns are infeasible.
|
2206.01940
|
Ali Alavi
|
S.A. Alavi and T. Fallahi. Serish
|
Neutrino spin oscillations in gravitational fields in higher dimensions
|
12 pages. Replaced with the version published in Modern Physics
Letters A
|
Modern Physics Letters A, Vol. 37, No. 30, 2250200 (2022)
|
10.1142/S0217732322502005
| null |
gr-qc astro-ph.HE hep-ph hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
Neutrino physics in one of the most active fields of research with important
implications for particle physics, cosmology and astrophysics. On the other
hand, motivated by some theories including string theory, formulation of
physical theories in more than four space-time dimensions has been the subject
of increasing attention in recent years. Interaction of neutrinos with
gravitational fields is one of the interesting phenomena which can lead to
transition between different helicity states (spin oscillations). We study
neutrino spin oscillations in Schwarzschild and RN backgrounds in higher
dimensional gravitational fields. We calculate the transition probability as a
function of time and also study the dependence of the oscillation frequency on
the orbital radius. The results help us to better understand the behavior of
gravity and neutrinos in higher dimensions.
|
[
{
"created": "Sat, 4 Jun 2022 08:35:52 GMT",
"version": "v1"
},
{
"created": "Mon, 16 Jan 2023 07:23:18 GMT",
"version": "v2"
}
] |
2023-01-18
|
[
[
"Alavi",
"S. A.",
""
],
[
"Serish",
"T. Fallahi.",
""
]
] |
Neutrino physics in one of the most active fields of research with important implications for particle physics, cosmology and astrophysics. On the other hand, motivated by some theories including string theory, formulation of physical theories in more than four space-time dimensions has been the subject of increasing attention in recent years. Interaction of neutrinos with gravitational fields is one of the interesting phenomena which can lead to transition between different helicity states (spin oscillations). We study neutrino spin oscillations in Schwarzschild and RN backgrounds in higher dimensional gravitational fields. We calculate the transition probability as a function of time and also study the dependence of the oscillation frequency on the orbital radius. The results help us to better understand the behavior of gravity and neutrinos in higher dimensions.
|
2002.11718
|
Ahmad Sheykhi
|
Ahmad Sheykhi
|
Mimetic Black Strings
|
21 pages, Accepted by JHEP
|
JHEP 07 (2020) 031
|
10.1007/JHEP07(2020)031
| null |
gr-qc hep-th
|
http://creativecommons.org/licenses/by/4.0/
|
We present two new classes of black string solutions in the context of
mimetic gravity. The horizon topology of these solutions can be either a flat
$T^2$ torus with topology $S^1 \times S^1$, or a standard cylindrical model
with topology $R\times S^1$. The first class describes uncharged rotating black
string which its asymptotic behavior is a quotient of anti-de Sitter (AdS)
space, while the second class represents asymptotically AdS charged rotating
black string. We study the casual structure and physical properties of these
spacetimes and calculate, the entropy, electric charge, mass and angular
momentum per unit length of rotating black strings.
|
[
{
"created": "Wed, 26 Feb 2020 15:54:40 GMT",
"version": "v1"
},
{
"created": "Tue, 3 Mar 2020 16:17:06 GMT",
"version": "v2"
},
{
"created": "Sat, 13 Jun 2020 09:02:00 GMT",
"version": "v3"
}
] |
2020-10-21
|
[
[
"Sheykhi",
"Ahmad",
""
]
] |
We present two new classes of black string solutions in the context of mimetic gravity. The horizon topology of these solutions can be either a flat $T^2$ torus with topology $S^1 \times S^1$, or a standard cylindrical model with topology $R\times S^1$. The first class describes uncharged rotating black string which its asymptotic behavior is a quotient of anti-de Sitter (AdS) space, while the second class represents asymptotically AdS charged rotating black string. We study the casual structure and physical properties of these spacetimes and calculate, the entropy, electric charge, mass and angular momentum per unit length of rotating black strings.
|
2001.07018
|
Ion I. Cotaescu
|
Ion I. Cotaescu
|
Rest frame vacuum of the Proca field on the de Sitter expanding universe
|
15 pages, no figures
| null | null | null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The general plane wave solutions of the Proca field in conformal charts of
the de Sitter expanding universe are derived for arbitrary polarizations
showing how the frequencies can be separated in rest frames, defining thus the
rest frame vacuum of this field.
|
[
{
"created": "Mon, 20 Jan 2020 08:43:35 GMT",
"version": "v1"
}
] |
2020-01-22
|
[
[
"Cotaescu",
"Ion I.",
""
]
] |
The general plane wave solutions of the Proca field in conformal charts of the de Sitter expanding universe are derived for arbitrary polarizations showing how the frequencies can be separated in rest frames, defining thus the rest frame vacuum of this field.
|
1702.04568
|
Borja Reina
|
Borja Reina, Nicolas Sanchis-Gual, Ra\"ul Vera, Jos\'e A. Font
|
Completion of the universal I-Love-Q relations in compact stars
including the mass
|
6 pages, 2 figures. Accepted for publication in MNRAS
| null |
10.1093/mnrasl/slx078
| null |
gr-qc astro-ph.HE
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In a recent paper we applied a rigorous perturbed matching framework to show
the amendment of the mass of rotating stars in Hartle's model. Here, we apply
this framework to the tidal problem in binary systems. Our approach fully
accounts for the correction to the Love numbers needed to obtain the universal
$I$-Love-$Q$ relations. We compute the corrected mass vs radius configurations
of rotating quark stars, revisiting a classical paper on the subject. These
corrections allow us to find a universal relation involving the second-order
contribution to the mass $\delta M$. We thus complete the set of universal
relations for the tidal problem in binary systems, involving four perturbation
parameters, namely $I$, Love, $Q$, and $\delta M$. These relations can be used
to obtain the perturbation parameters directly from observational data.
|
[
{
"created": "Wed, 15 Feb 2017 12:09:14 GMT",
"version": "v1"
},
{
"created": "Mon, 15 May 2017 14:45:16 GMT",
"version": "v2"
}
] |
2017-07-26
|
[
[
"Reina",
"Borja",
""
],
[
"Sanchis-Gual",
"Nicolas",
""
],
[
"Vera",
"Raül",
""
],
[
"Font",
"José A.",
""
]
] |
In a recent paper we applied a rigorous perturbed matching framework to show the amendment of the mass of rotating stars in Hartle's model. Here, we apply this framework to the tidal problem in binary systems. Our approach fully accounts for the correction to the Love numbers needed to obtain the universal $I$-Love-$Q$ relations. We compute the corrected mass vs radius configurations of rotating quark stars, revisiting a classical paper on the subject. These corrections allow us to find a universal relation involving the second-order contribution to the mass $\delta M$. We thus complete the set of universal relations for the tidal problem in binary systems, involving four perturbation parameters, namely $I$, Love, $Q$, and $\delta M$. These relations can be used to obtain the perturbation parameters directly from observational data.
|
2206.06601
|
Amarkumar Agrawal
|
A.S. Agrawal, B. Mishra, S.K. Tripathy
|
Observationally constrained accelerating cosmological model with higher
power of non-metricity and squared trace
|
14 pages, 9 figures
|
Journal of High Energy Astrophysics, 38, 2023, 41-48
|
10.1016/j.jheap.2023.04.001
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this paper, a cosmological model of the Universe is presented in $f(Q,T)$
gravity and the parameters are constrained by cosmological data sets.
Initially, a generalised form of $f(Q,T)$ model is used as $f(Q,T)=-\lambda_{1}
Q^{m}-\lambda_{2} T^2$, where $\lambda_{1}$, $\lambda_{2}$ and $m$ are model
parameters. With some algebraic manipulation, the Hubble parameter is obtained
in terms of redshift. Then, using MCMC analysis, the model parameters are
constrained using the most current Hubble and Pantheon$^{+}$ data. The model
parameters are also verified through the BAO data set. The model shows an early
deceleration transitioning to an accelerating phase of the Universe. The
$Om(z)$ diagnostics indicate a positive slope, favouring the model to be in a
phantom field dominated phase.
|
[
{
"created": "Tue, 14 Jun 2022 05:43:38 GMT",
"version": "v1"
},
{
"created": "Wed, 10 May 2023 12:29:16 GMT",
"version": "v2"
}
] |
2024-03-21
|
[
[
"Agrawal",
"A. S.",
""
],
[
"Mishra",
"B.",
""
],
[
"Tripathy",
"S. K.",
""
]
] |
In this paper, a cosmological model of the Universe is presented in $f(Q,T)$ gravity and the parameters are constrained by cosmological data sets. Initially, a generalised form of $f(Q,T)$ model is used as $f(Q,T)=-\lambda_{1} Q^{m}-\lambda_{2} T^2$, where $\lambda_{1}$, $\lambda_{2}$ and $m$ are model parameters. With some algebraic manipulation, the Hubble parameter is obtained in terms of redshift. Then, using MCMC analysis, the model parameters are constrained using the most current Hubble and Pantheon$^{+}$ data. The model parameters are also verified through the BAO data set. The model shows an early deceleration transitioning to an accelerating phase of the Universe. The $Om(z)$ diagnostics indicate a positive slope, favouring the model to be in a phantom field dominated phase.
|
1506.01869
|
Thomas-Paul Hack
|
Thomas-Paul Hack
|
Cosmological Applications of Algebraic Quantum Field Theory in Curved
Spacetimes
|
123 pages, 4 figures, to appear as SpringerBriefs in Mathematical
Physics
| null | null | null |
gr-qc hep-th math-ph math.MP
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
This monograph provides a largely self--contained and broadly accessible
exposition of two cosmological applications of algebraic quantum field theory
(QFT) in curved spacetime: a fundamental analysis of the cosmological evolution
according to the Standard Model of Cosmology and a fundamental study of the
perturbations in Inflation. The two central sections of the book dealing with
these applications are preceded by sections containing a pedagogical
introduction to the subject as well as introductory material on the
construction of linear QFTs on general curved spacetimes with and without gauge
symmetry in the algebraic approach, physically meaningful quantum states on
general curved spacetimes, and the backreaction of quantum fields in curved
spacetimes via the semiclassical Einstein equation. The target reader should
have a basic understanding of General Relativity and QFT on Minkowski
spacetime, but does not need to have a background in QFT on curved spacetimes
or the algebraic approach to QFT. In particular, I took a great deal of care to
provide a thorough motivation for all concepts of algebraic QFT touched upon in
this monograph, as they partly may seem rather abstract at first glance. Thus,
it is my hope that this work can help non--experts to make `first contact' with
the algebraic approach to QFT.
|
[
{
"created": "Fri, 5 Jun 2015 11:27:33 GMT",
"version": "v1"
}
] |
2015-06-08
|
[
[
"Hack",
"Thomas-Paul",
""
]
] |
This monograph provides a largely self--contained and broadly accessible exposition of two cosmological applications of algebraic quantum field theory (QFT) in curved spacetime: a fundamental analysis of the cosmological evolution according to the Standard Model of Cosmology and a fundamental study of the perturbations in Inflation. The two central sections of the book dealing with these applications are preceded by sections containing a pedagogical introduction to the subject as well as introductory material on the construction of linear QFTs on general curved spacetimes with and without gauge symmetry in the algebraic approach, physically meaningful quantum states on general curved spacetimes, and the backreaction of quantum fields in curved spacetimes via the semiclassical Einstein equation. The target reader should have a basic understanding of General Relativity and QFT on Minkowski spacetime, but does not need to have a background in QFT on curved spacetimes or the algebraic approach to QFT. In particular, I took a great deal of care to provide a thorough motivation for all concepts of algebraic QFT touched upon in this monograph, as they partly may seem rather abstract at first glance. Thus, it is my hope that this work can help non--experts to make `first contact' with the algebraic approach to QFT.
|
1403.1014
|
Behrouz Mirza
|
Mohamadreza Fazel, Behrouz Mirza, Seyed Ali Hosseini Mansoori
|
Black hole temperature: minimal coupling vs conformal coupling
|
20 pages, 1 figure, references added
|
Annals of Physics 344 (2014) 232-252
|
10.1016/j.aop.2014.02.020
| null |
gr-qc hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In this article, we discuss the propagation of scalar fields in conformally
transformed spacetimes with either minimal or conformal coupling. The
conformally coupled equation of motion is transformed into a one-dimensional
Schr\"{o}dinger-like equation with an invariant potential under conformal
transformation. In a second stage, we argue that calculations based on
conformal coupling yield the same Hawking temperature as those based on minimal
coupling. Finally, it is conjectured that the quasi normal modes of black holes
are invariant under conformal transformation.
|
[
{
"created": "Wed, 5 Mar 2014 06:32:17 GMT",
"version": "v1"
},
{
"created": "Sat, 14 Jun 2014 09:40:53 GMT",
"version": "v2"
}
] |
2015-06-19
|
[
[
"Fazel",
"Mohamadreza",
""
],
[
"Mirza",
"Behrouz",
""
],
[
"Mansoori",
"Seyed Ali Hosseini",
""
]
] |
In this article, we discuss the propagation of scalar fields in conformally transformed spacetimes with either minimal or conformal coupling. The conformally coupled equation of motion is transformed into a one-dimensional Schr\"{o}dinger-like equation with an invariant potential under conformal transformation. In a second stage, we argue that calculations based on conformal coupling yield the same Hawking temperature as those based on minimal coupling. Finally, it is conjectured that the quasi normal modes of black holes are invariant under conformal transformation.
|
1408.2689
|
Manuel Rodrigues
|
M. E. Rodrigues, A. V. Kpadonou, F. Rahaman, P. J. Oliveira and M. J.
S. Houndjo
|
Bianchi type-I, type-III and Kantowski-Sachs solutions in f(T) gravity
|
19 pages, 3 figures
|
Astrophys Space Sci (2015) 357:129
|
10.1007/s10509-015-2358-8
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
In the context of modified tele-parallel theory of gravity, we undertake
cosmological anisotropic models and search for their solutions. Within a
suitable choice of non-diagonal tetrads, the decoupled equations of motion are
obtained for Bianchi-I, Bianchi-III and Kantowski-Sachs models, from which we
obtain the correspondent solutions. By the way, energy density and pressures
are also obtained, showing, as an important result, that our universe may live
a quintessence like universe even still anisotropic models are considered.
|
[
{
"created": "Tue, 12 Aug 2014 10:55:25 GMT",
"version": "v1"
}
] |
2015-06-25
|
[
[
"Rodrigues",
"M. E.",
""
],
[
"Kpadonou",
"A. V.",
""
],
[
"Rahaman",
"F.",
""
],
[
"Oliveira",
"P. J.",
""
],
[
"Houndjo",
"M. J. S.",
""
]
] |
In the context of modified tele-parallel theory of gravity, we undertake cosmological anisotropic models and search for their solutions. Within a suitable choice of non-diagonal tetrads, the decoupled equations of motion are obtained for Bianchi-I, Bianchi-III and Kantowski-Sachs models, from which we obtain the correspondent solutions. By the way, energy density and pressures are also obtained, showing, as an important result, that our universe may live a quintessence like universe even still anisotropic models are considered.
|
2008.09957
|
Chinmay Kalaghatgi Mr.
|
Chinmay Kalaghatgi and Mark Hannam
|
Investigating the effect of in-plane spin directions for Precessing BBH
systems
|
13 pages, 8 figures
|
Phys. Rev. D 103, 024024 (2021)
|
10.1103/PhysRevD.103.024024
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Morphology of coalescing BBH waveforms are affected by its spins. Waveform
models built for inference of source parameters have several in-built
approximations. In current precessing IMRPhenom and SEOBNR waveform models,
systems with the same spin magnitude but varying orientation of spins projected
on the orbital plane are effectively mapped to the same system (bar an overall
phase change) and the asymmetry due to precession between the $+m$ and $-m$
modes is not modelled. In this study, we investigate the validity of these
approximations by generating numerical relativity (NR) simulations of
single-spin NR systems with varying in-plane spin directions (including several
superkick configurations) and provide an estimate of the SNR at which the
effect of varying in-plane spin directions would be measurable. This is done
computing the match between these waveforms and using these match values to
estimate the distinguishability SNR. We also use NR waveforms with different
spin magnitudes to compare the measurability of spin magnitude vs. in-plane
spin direction. We find that the in-plane spin direction could be measurable at
SNRs accessible by current generation detectors, with the distinguishability
SNR of varying in-plane spins comparable to or lower than varying the in-plane
spin magnitude. We then remove the mode-asymmetry content from the waveforms
and find that, i) removing mode-asymmetry increases the SNR at which in-plane
spin direction can be measured and ii) not modelling mode-asymmetry will lead
to measurement biases. The SNRs that we see at which the in-plane spins would
be measurable and at which mode-asymmetric content impacts the measurements are
the SNRs at which precession would be measurable, and we therefore conclude
that modelling in-plane spin direction and mode-asymmetry effects is necessary
for unbiassed measurements of precession.
|
[
{
"created": "Sun, 23 Aug 2020 04:48:57 GMT",
"version": "v1"
},
{
"created": "Wed, 27 Jan 2021 05:40:37 GMT",
"version": "v2"
}
] |
2021-01-28
|
[
[
"Kalaghatgi",
"Chinmay",
""
],
[
"Hannam",
"Mark",
""
]
] |
Morphology of coalescing BBH waveforms are affected by its spins. Waveform models built for inference of source parameters have several in-built approximations. In current precessing IMRPhenom and SEOBNR waveform models, systems with the same spin magnitude but varying orientation of spins projected on the orbital plane are effectively mapped to the same system (bar an overall phase change) and the asymmetry due to precession between the $+m$ and $-m$ modes is not modelled. In this study, we investigate the validity of these approximations by generating numerical relativity (NR) simulations of single-spin NR systems with varying in-plane spin directions (including several superkick configurations) and provide an estimate of the SNR at which the effect of varying in-plane spin directions would be measurable. This is done computing the match between these waveforms and using these match values to estimate the distinguishability SNR. We also use NR waveforms with different spin magnitudes to compare the measurability of spin magnitude vs. in-plane spin direction. We find that the in-plane spin direction could be measurable at SNRs accessible by current generation detectors, with the distinguishability SNR of varying in-plane spins comparable to or lower than varying the in-plane spin magnitude. We then remove the mode-asymmetry content from the waveforms and find that, i) removing mode-asymmetry increases the SNR at which in-plane spin direction can be measured and ii) not modelling mode-asymmetry will lead to measurement biases. The SNRs that we see at which the in-plane spins would be measurable and at which mode-asymmetric content impacts the measurements are the SNRs at which precession would be measurable, and we therefore conclude that modelling in-plane spin direction and mode-asymmetry effects is necessary for unbiassed measurements of precession.
|
gr-qc/9406016
| null |
P. Menotti and D. Seminara
|
Energy Theorem for 2+1 dimensional gravity
|
(Revtex), 24 pages,MIT-CTP#2324 snd IFUP-TH-33/94
|
Annals Phys. 240 (1995) 203-221
|
10.1006/aphy.1995.1044
| null |
gr-qc hep-th
| null |
We prove a positive energy theorem in 2+1 dimensional gravity for open
universes and any matter energy-momentum tensor satisfying the dominant energy
condition. We consider on the space-like initial value surface a family of
widening Wilson loops and show that the energy-momentum of the enclosed
subsystem is a future directed time-like vector whose mass is an increasing
function of the loop, until it reaches the value $1/4G$ corresponding to a
deficit angle of $2\pi$. At this point the energy-momentum of the system
evolves, depending on the nature of a zero norm vector appearing in the
evolution equations, either into a time-like vector of a universe which closes
kinematically or into a Gott-like universe whose energy momentum vector, as
first recognized by Deser, Jackiw and 't Hooft is space-like.
This treatment generalizes results obtained by Carroll, Fahri, Guth and Olum
for a system of point-like spinless particle, to the most general form of
matter whose energy-momentum tensor satisfies the dominant energy condition.
The treatment is also given for the anti de Sitter 2+1 dimensional gravity.
|
[
{
"created": "Wed, 8 Jun 1994 21:49:33 GMT",
"version": "v1"
}
] |
2009-10-22
|
[
[
"Menotti",
"P.",
""
],
[
"Seminara",
"D.",
""
]
] |
We prove a positive energy theorem in 2+1 dimensional gravity for open universes and any matter energy-momentum tensor satisfying the dominant energy condition. We consider on the space-like initial value surface a family of widening Wilson loops and show that the energy-momentum of the enclosed subsystem is a future directed time-like vector whose mass is an increasing function of the loop, until it reaches the value $1/4G$ corresponding to a deficit angle of $2\pi$. At this point the energy-momentum of the system evolves, depending on the nature of a zero norm vector appearing in the evolution equations, either into a time-like vector of a universe which closes kinematically or into a Gott-like universe whose energy momentum vector, as first recognized by Deser, Jackiw and 't Hooft is space-like. This treatment generalizes results obtained by Carroll, Fahri, Guth and Olum for a system of point-like spinless particle, to the most general form of matter whose energy-momentum tensor satisfies the dominant energy condition. The treatment is also given for the anti de Sitter 2+1 dimensional gravity.
|
1209.5232
|
Mustapha Azreg-A\"inou
|
Mustapha Azreg-A\"inou
|
Light paths of normal and phantom Einstein-Maxwell-dilaton black holes
|
30 pages, 14 figures (with 7 captions), minor corrections
|
Phys. Rev. D 87, 024012 (2013)
|
10.1103/PhysRevD.87.024012
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Null geodesics of normal and phantom Einstein-Maxwell-dilaton black holes are
determined analytically by the Weierstrass elliptic functions. The black hole
parameters other than the mass enter, with the appropriate signs, the formula
for the angle of deflection to the second order in the inverse of the impact
parameter allowing for the identification of the nature of matter (phantom or
normal). Such identification is also possible via the time delay formula and
observation of relativistic images. Scattering experiencesmay favor black holes
of Einstein-anti-Maxwell-dilatonic theory for their high relative discrepancy
with respect to the Schwarzschild value. For the cases we restrict ourselves
to, phantom black holes are characterized by the absence of many-world and
two-world null geodesics.
|
[
{
"created": "Mon, 24 Sep 2012 11:34:21 GMT",
"version": "v1"
},
{
"created": "Mon, 24 Dec 2012 14:22:48 GMT",
"version": "v2"
},
{
"created": "Mon, 7 Jan 2013 17:51:50 GMT",
"version": "v3"
}
] |
2013-01-08
|
[
[
"Azreg-Aïnou",
"Mustapha",
""
]
] |
Null geodesics of normal and phantom Einstein-Maxwell-dilaton black holes are determined analytically by the Weierstrass elliptic functions. The black hole parameters other than the mass enter, with the appropriate signs, the formula for the angle of deflection to the second order in the inverse of the impact parameter allowing for the identification of the nature of matter (phantom or normal). Such identification is also possible via the time delay formula and observation of relativistic images. Scattering experiencesmay favor black holes of Einstein-anti-Maxwell-dilatonic theory for their high relative discrepancy with respect to the Schwarzschild value. For the cases we restrict ourselves to, phantom black holes are characterized by the absence of many-world and two-world null geodesics.
|
1202.2830
|
Manuel Rodrigues
|
Deborah F. Jardim, Manuel E. Rodrigues and M. J. S. Houndjo
|
Thermodynamics of phantom Reissner-Nordstrom-AdS black hole
|
13 pages, 11 figures
|
Eur. Phys. J. Plus 127: 123 (2012)
|
10.1140/epjp/i2012-12123-x
| null |
gr-qc astro-ph.CO hep-th
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We obtain a new solution of the Einstein-anti-Maxwell theory with
cosmological constant, called anti-Reissner-Nordstrom-(A)de Sitter
(anti-RN-(A)dS) solution. The basic properties of this solution is reviewed.
Its thermodynamics is consistently established, with the extreme cases and
phase transitions, where the analysis is performed through two methods, the
usual one and that of Geometrothermodynamics . The Geometrothermodynamics
analysis does not provide a result in agreement with the usual method or by the
specific heat. We establish local and global thermodynamic stabilities of
anti-RN-AdS solution through the specific heat and the canonical and
grand-canonical ensembles.
|
[
{
"created": "Mon, 13 Feb 2012 19:53:21 GMT",
"version": "v1"
},
{
"created": "Wed, 22 Feb 2012 13:28:23 GMT",
"version": "v2"
},
{
"created": "Wed, 3 Oct 2012 19:53:21 GMT",
"version": "v3"
}
] |
2012-10-04
|
[
[
"Jardim",
"Deborah F.",
""
],
[
"Rodrigues",
"Manuel E.",
""
],
[
"Houndjo",
"M. J. S.",
""
]
] |
We obtain a new solution of the Einstein-anti-Maxwell theory with cosmological constant, called anti-Reissner-Nordstrom-(A)de Sitter (anti-RN-(A)dS) solution. The basic properties of this solution is reviewed. Its thermodynamics is consistently established, with the extreme cases and phase transitions, where the analysis is performed through two methods, the usual one and that of Geometrothermodynamics . The Geometrothermodynamics analysis does not provide a result in agreement with the usual method or by the specific heat. We establish local and global thermodynamic stabilities of anti-RN-AdS solution through the specific heat and the canonical and grand-canonical ensembles.
|
2109.00056
|
Thomas Osburn
|
Jonathan McCart and Thomas Osburn and Justin Y. J. Burton
|
Highly eccentric EMRI waveforms via fast self-forced inspirals
|
14 pages, 8 figures, updated to more closely match published version
|
Phys. Rev. D 104, 084050 (2021)
|
10.1103/PhysRevD.104.084050
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
We present new developments and comparisons of competing inspiral and
waveform models for highly eccentric non-spinning extreme and intermediate
mass-ratio inspirals (EMRIs and IMRIs). Starting from our high eccentricity
self-force library, we apply the near-identity transform (NIT) technique to
rapidly compute highly eccentric self-forced inspirals for the first time. Upon
evaluating our approximate NIT results via comparison with full self-force
inspirals, we couple our accurate and streamlined inspiral data to potential
waveform generation schemes. We find that, although high eccentricity strains
the NIT method, NIT inspirals are consistent with full self-force inspirals for
EMRIs. However, our NIT implementation (at 1st post-adiabatic order) is not
able to achieve LISA-motivated accuracy goals for highly eccentric IMRIs. Our
most sophisticated waveforms are devised through a new technique that
efficiently connects NIT orbital parameters to Teukolsky amplitudes and phases.
We compare these sophisticated Teukolsky waveforms to those with synthesized
(summing over harmonics) amplitudes based on a kludge. We find that, assuming
identical worldlines (so that dephasing is negligible), kludge waveforms
compare favorably to Teukolsky waveforms for non-spinning bodies.
|
[
{
"created": "Tue, 31 Aug 2021 19:42:17 GMT",
"version": "v1"
},
{
"created": "Wed, 13 Oct 2021 21:45:31 GMT",
"version": "v2"
}
] |
2021-10-15
|
[
[
"McCart",
"Jonathan",
""
],
[
"Osburn",
"Thomas",
""
],
[
"Burton",
"Justin Y. J.",
""
]
] |
We present new developments and comparisons of competing inspiral and waveform models for highly eccentric non-spinning extreme and intermediate mass-ratio inspirals (EMRIs and IMRIs). Starting from our high eccentricity self-force library, we apply the near-identity transform (NIT) technique to rapidly compute highly eccentric self-forced inspirals for the first time. Upon evaluating our approximate NIT results via comparison with full self-force inspirals, we couple our accurate and streamlined inspiral data to potential waveform generation schemes. We find that, although high eccentricity strains the NIT method, NIT inspirals are consistent with full self-force inspirals for EMRIs. However, our NIT implementation (at 1st post-adiabatic order) is not able to achieve LISA-motivated accuracy goals for highly eccentric IMRIs. Our most sophisticated waveforms are devised through a new technique that efficiently connects NIT orbital parameters to Teukolsky amplitudes and phases. We compare these sophisticated Teukolsky waveforms to those with synthesized (summing over harmonics) amplitudes based on a kludge. We find that, assuming identical worldlines (so that dephasing is negligible), kludge waveforms compare favorably to Teukolsky waveforms for non-spinning bodies.
|
1412.1662
|
Giovanni Manfredi
|
Giovanni Manfredi
|
The Schr\"odinger-Newton equations beyond Newton
|
To appear in General Relativity and Gravitation
| null |
10.1007/s10714-014-1846-4
| null |
gr-qc quant-ph
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
The scope of this paper is twofold. First, we derive rigorously a
low-velocity and Galilei-covariant limit of the gravitoelectromagnetic (GEM)
equations. Subsequently, these reduced GEM equations are coupled to the
Schr\"odinger equation with gravitoelectric and gravitomagnetic potentials. The
resulting extended Schr\"odinger-Newton equations constitute a minimal model
where the three fundamental constants of nature ($G$, $\hbar$, and $c$) appear
naturally. We show that the relativistic correction coming from the
gravitomagnetic potential scales as the ratio of the mass of the system to the
Planck mass, and that it reinforces the standard Newtonian (gravitoelectric)
attraction. The theory is further generalized to many particles through a
Wigner function approach.
|
[
{
"created": "Thu, 4 Dec 2014 13:37:42 GMT",
"version": "v1"
}
] |
2015-06-23
|
[
[
"Manfredi",
"Giovanni",
""
]
] |
The scope of this paper is twofold. First, we derive rigorously a low-velocity and Galilei-covariant limit of the gravitoelectromagnetic (GEM) equations. Subsequently, these reduced GEM equations are coupled to the Schr\"odinger equation with gravitoelectric and gravitomagnetic potentials. The resulting extended Schr\"odinger-Newton equations constitute a minimal model where the three fundamental constants of nature ($G$, $\hbar$, and $c$) appear naturally. We show that the relativistic correction coming from the gravitomagnetic potential scales as the ratio of the mass of the system to the Planck mass, and that it reinforces the standard Newtonian (gravitoelectric) attraction. The theory is further generalized to many particles through a Wigner function approach.
|
2203.12766
|
Yurii Ignat'ev
|
Yu. G. Ignat'ev, A.A. Agathonov and D. Yu. Ignatyev
|
Cosmological evolution of a statistical system of degenerate scalar
charged fermions with an asymmetric scalar doublet. II. One-component system
of doubly charged fermions
|
15 pages, 15 figures, 22 references. arXiv admin note: text overlap
with arXiv:2203.11946
|
Gravit. Cosmol. 28 (2022) 10
|
10.1134/S0202289322010066
| null |
gr-qc
|
http://arxiv.org/licenses/nonexclusive-distrib/1.0/
|
Based on the previously formulated mathematical model of a statistical system
with scalar interaction of fermions, a cosmological model based on a
one-component statistical system of doubly scalar charged degenerate fermions
interacting with an asymmetric scalar doublet-canonical and phantom scalar
fields-is studied. The connection of the presented model with previously
studied models based on one-component and two-component fermion systems is
investigated. The asymptotic and limiting properties of the cosmological model
are investigated, it is shown that among all models there is a class of models
with a finite lifetime. The asymptotic behavior of models near the
corresponding singularities is investigated, a qualitative analysis of the
corresponding dynamical system is carried out, and numerical implementations of
such models are constructed. Based on numerical integration, it is shown that
in the presented model there can be transitions from a stable asymptotically
vacuum state with a zero canonical field and a constant phantom field
corresponding to the phase of cosmological compression to a symmetric state
corresponding to the expansion phase. The time interval of the transition
between phases is accompanied by oscillations of the canonical scalar field.
|
[
{
"created": "Tue, 22 Mar 2022 16:28:29 GMT",
"version": "v1"
}
] |
2022-03-25
|
[
[
"Ignat'ev",
"Yu. G.",
""
],
[
"Agathonov",
"A. A.",
""
],
[
"Ignatyev",
"D. Yu.",
""
]
] |
Based on the previously formulated mathematical model of a statistical system with scalar interaction of fermions, a cosmological model based on a one-component statistical system of doubly scalar charged degenerate fermions interacting with an asymmetric scalar doublet-canonical and phantom scalar fields-is studied. The connection of the presented model with previously studied models based on one-component and two-component fermion systems is investigated. The asymptotic and limiting properties of the cosmological model are investigated, it is shown that among all models there is a class of models with a finite lifetime. The asymptotic behavior of models near the corresponding singularities is investigated, a qualitative analysis of the corresponding dynamical system is carried out, and numerical implementations of such models are constructed. Based on numerical integration, it is shown that in the presented model there can be transitions from a stable asymptotically vacuum state with a zero canonical field and a constant phantom field corresponding to the phase of cosmological compression to a symmetric state corresponding to the expansion phase. The time interval of the transition between phases is accompanied by oscillations of the canonical scalar field.
|
gr-qc/0205113
|
K. H. Mariwalla
|
K. H. Mariwalla
|
Gravity sans singularities
|
7 pages
| null | null | null |
gr-qc hep-th
| null |
Basis and limitations of singularity theorems for Gravity are examined. As
singularity is a critical situation in course of time, study of time paths, in
full generality of Equivalence principle, provides two mechanisms to prevent
singularity. Resolution of singular Time translation generators into space of
its orbits, and essential higher dimensions for Relativistic particle
interactions has facets to resolve any real singularity problem. Conceptually,
these varied viewpoints have a common denominator: arbitrariness in the
definition of `energy' intrinsic to the space of operation in each case, so as
to render absence of singularity a tautology for self-consistency of the
systems.
|
[
{
"created": "Tue, 28 May 2002 10:41:35 GMT",
"version": "v1"
}
] |
2007-05-23
|
[
[
"Mariwalla",
"K. H.",
""
]
] |
Basis and limitations of singularity theorems for Gravity are examined. As singularity is a critical situation in course of time, study of time paths, in full generality of Equivalence principle, provides two mechanisms to prevent singularity. Resolution of singular Time translation generators into space of its orbits, and essential higher dimensions for Relativistic particle interactions has facets to resolve any real singularity problem. Conceptually, these varied viewpoints have a common denominator: arbitrariness in the definition of `energy' intrinsic to the space of operation in each case, so as to render absence of singularity a tautology for self-consistency of the systems.
|
gr-qc/9404033
|
M. Rainer
|
M. Rainer
|
Conformal Coupling and Invariance in Different Dimensions
|
revised version (accepted by Int. J. Mod. Phys. D, ed.: A. Ashtekar,
2-Nov-94), 23 pages, LATEX, Uni Potsdam MATH-94/02
|
Int.J.Mod.Phys. D4 (1995) 397-416
|
10.1142/S0218271895000302
| null |
gr-qc hep-th
| null |
Conformal transformations of the following kinds are compared: (1) conformal
coordinate transformations, (2) conformal transformations of Lagrangian models
for a D-dimensional geometry, given by a Riemannian manifold M with metric g of
arbitrary signature, and (3) conformal transformations of (mini-)superspace
geometry. For conformal invariance under this transformations the following
applications are given respectively: (1) Natural time gauges for
multidimensional geometry, (2) conformally equivalent Lagrangian models for
geometry coupled to a spacially homogeneous scalar field, and (3) the conformal
Laplace operator on the $n$-dimensional manifold $M of minisuperspace for
multidimensional geometry and the Wheeler de Witt equation. The conformal
coupling constant xi_c is critically distinguished among arbitrary couplings
xi, for both, the equivalence of Lagrangian models with D-dimensional geometry
and the conformal geometry on n-dimensional minisuperspace. For dimension
D=3,4,6 or 10, the critical number xi_c={D-2}/{4(D-1)} is especially simple as
a rational fraction.
|
[
{
"created": "Sun, 17 Apr 1994 19:02:04 GMT",
"version": "v1"
},
{
"created": "Mon, 14 Nov 1994 21:30:41 GMT",
"version": "v2"
}
] |
2009-10-22
|
[
[
"Rainer",
"M.",
""
]
] |
Conformal transformations of the following kinds are compared: (1) conformal coordinate transformations, (2) conformal transformations of Lagrangian models for a D-dimensional geometry, given by a Riemannian manifold M with metric g of arbitrary signature, and (3) conformal transformations of (mini-)superspace geometry. For conformal invariance under this transformations the following applications are given respectively: (1) Natural time gauges for multidimensional geometry, (2) conformally equivalent Lagrangian models for geometry coupled to a spacially homogeneous scalar field, and (3) the conformal Laplace operator on the $n$-dimensional manifold $M of minisuperspace for multidimensional geometry and the Wheeler de Witt equation. The conformal coupling constant xi_c is critically distinguished among arbitrary couplings xi, for both, the equivalence of Lagrangian models with D-dimensional geometry and the conformal geometry on n-dimensional minisuperspace. For dimension D=3,4,6 or 10, the critical number xi_c={D-2}/{4(D-1)} is especially simple as a rational fraction.
|
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