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arxiv_dataset-300710.3053 | Group Analysis of Variable Coefficient Diffusion--Convection Equations.
III. Conservation Laws
math-ph math.MP
The notions of generating sets of conservation laws of systems of
differential equations with respect to symmetry groups and equivalence groups
are introduced and applied. This allows us to generalize essentially the
procedure of finding potential symmetries for the systems with multidimensional
spaces of conservation laws. A class of variable coefficient (1+1)-dimensional
nonlinear diffusion-convection equations of general form
$f(x)u_t=(g(x)A(u)u_x)_x+h(x)B(u)u_x$ is investigated. Using the most direct
method, we carry out two classifications of local conservation laws up to
equivalence relations generated by both usual and enhanced equivalence groups.
Equivalence with respect to $\hat G^{\sim}$ and correct choice of gauge
coefficients of equations play the major role for simple and clear formulation
of the final results. The notion of contractions of conservation laws and one
of characteristics of conservation laws are introduced and contractions of
conservation laws of diffusion-convection equations are found.
| arxiv topic:math-ph math.MP |
arxiv_dataset-301710.3153 | Electronic correlation in nanoscale junctions: Comparison of the GW
approximation to a numerically exact solution of the single-impurity Anderson
model
cond-mat.mtrl-sci cond-mat.str-el
The impact of electronic correlation in nanoscale junctions, e.g. formed by
single molecules, is analyzed using the single-impurity Anderson model.
Numerically exact Quantum Monte Carlo calculations are performed to map out the
orbital filling, linear response conductance and spectral function as a
function of the Coulomb interaction strength and the impurity level position.
These numerical results form a benchmark against which approximate, but more
broadly applicable, approaches to include electronic correlation in transport
can be compared. As an example, the self consistent GW approximation has been
implemented for the Anderson model and the results compared to this benchmark.
For weak coupling or for level positions such that the impurity is either
nearly empty or nearly full, the GW approximation is found to be accurate.
However, for intermediate or strong coupling, the GW approximation does not
properly represent the impact of spin or charge fluctuations. Neither the
spectral function nor the linear response conductance are accurately given
across the Coulomb blockade plateau and well into the mixed valence regimes.
| arxiv topic:cond-mat.mtrl-sci cond-mat.str-el |
arxiv_dataset-302710.3253 | Two Paradoxes of the Existence of electric Charge
physics.gen-ph
Electromagnetic waves propagate with the speed of light. The reason is that
electrostatic fields as well as magnetic fields propagate with this speed. Both
types of objects, waves as well as static fields contain and transport energy.
Consequently it is possible to calculate how much energy and how much energy
density a source of a field emits into the space - and the calculation shows
that this energy is not zero, for elementary particles as well as for
macroscopic spheres. The calculation is presented in this article.
This leads to a principle problem not being answered up to now: From where
does the static charge obtain the energy, which it emits permantently? But the
paradox has a second aspect: If we follow the trace of a specified element of
volume containing an electric field on its way through the space, we will
notice that its contents of field energy decreases during time. But where does
this effluent energy go?
| arxiv topic:physics.gen-ph |
arxiv_dataset-303710.3353 | Roadmap for ILC Detector R&D Test Beams
physics.ins-det
This document provides a roadmap for ILC detector test beam needs in the next
3 - 5 years. In this period, detector Letters of Intent are expected by fall
2008, the ILC Engineering Design Report to be submitted in ILC and its
detectors in 2012. ILC detectors are required to have unprecedented precision
to be able to elucidate new physics discoveries at TeV energies from the LHC
and ILC machines, and to fully exploit experimental investifation at the
electrweak unification energy scale. Ahieving this requires significant
investment for detector test beam activities to complete the R&D needed, to
test prototypes and (later) to qualify final detector system desgns, including
integated system tess. This roadmap document describes the need for significant
increases in resources for ILC test beam activities. It should be used by test
beam facility managers and the worldwide ILC leadership to assure that the
necessary resources and facilities are made available to meet the needs in
time.
| arxiv topic:physics.ins-det |
arxiv_dataset-304710.3453 | Inefficient quantum walks on networks: the role of the density of states
quant-ph cond-mat.stat-mech
We show by general arguments that networks whose density of states contains
few highly degenerate eigenvalues result in inefficient performances of
continuous-time quantum walks (CTQW) over these networks, while systems whose
eigenvalues all have the same degeneracy lead to very efficient transport. We
exemplify our results by considering CTQW and, for comparison, its classical
counterpart, continuous-time random walks, over simple structures, whose
eigenvalues and eigenstates can be calculated analytically. Extensions to more
complicated, hyper-branched networks are discussed.
| arxiv topic:quant-ph cond-mat.stat-mech |
arxiv_dataset-305710.3553 | Homotopical interpretation of globular complex by multipointed d-space
math.AT math.CT
Globular complexes were introduced by E. Goubault and the author in
arXiv:math/0107060 to model higher dimensional automata. Globular complexes are
topological spaces equipped with a globular decomposition which is the directed
analogue of the cellular decomposition of a CW-complex. We prove that there
exists a combinatorial model category such that the cellular objects are
exactly the globular complexes and such that the homotopy category is
equivalent to the homotopy category of flows introduced in arXiv:math/0308054.
The underlying category of this model category is a variant of M. Grandis'
notion of d-space over a topological space colimit generated by simplices. This
result enables us to understand the relationship between the framework of flows
and other works in directed algebraic topology using d-spaces. It also enables
us to prove that the underlying homotopy type functor of flows constructed in
arXiv:math/0308063 can be interpreted up to equivalences of categories as the
total left derived functor of a left Quillen adjoint.
| arxiv topic:math.AT math.CT |
arxiv_dataset-306710.3653 | Slow-light enhanced optical detection in liquid-infiltrated photonic
crystals
physics.optics
Slow-light enhanced optical detection in liquid-infiltrated photonic crystals
is theoretically studied. Using a scattering-matrix approach and the
Wigner-Smith delay time concept, we show that optical absorbance benefits both
from slow-light phenomena as well as a high filling factor of the energy
residing in the liquid. Utilizing strongly dispersive photonic crystal
structures, we numerically demonstrate how liquid-infiltrated photonic crystals
facilitate enhanced light-matter interactions, by potentially up to an order of
magnitude. The proposed concept provides strong opportunities for improving
existing miniaturized absorbance cells for optical detection in lab-on-a-chip
systems.
| arxiv topic:physics.optics |
arxiv_dataset-307710.3753 | A very faint core-collapse supernova in M85
astro-ph
An anomalous transient in the early Hubble-type (S0) galaxy Messier 85 (M85)
in the Virgo cluster was discovered by Kulkarni et al. (2007) on 7 January 2006
that had very low luminosity (peak absolute R-band magnitude MR of about -12)
that was constant over more than 80 days, red colour and narrow spectral lines,
which seem inconsistent with those observed in any known class of transient
events. Kulkarni et al. (2007) suggest an exotic stellar merger as the possible
origin. An alternative explanation is that the transient in M85 was a type
II-plateau supernova of extremely low luminosity, exploding in a lenticular
galaxy with residual star-forming activity. This intriguing transient might be
the faintest supernova that has ever been discovered.
| arxiv topic:astro-ph |
arxiv_dataset-308710.3853 | Hopf modules for autonomous pseudomonoids and the monoidal centre
math.CT math.QA
In this work we develop some aspects of the theory of Hopf algebras to the
context of autonomous map pseudomonoids. We concentrate in the Hopf modules and
the Centre or Drinfel'd double. If $A$ is a map pseudomonoid in a monoidal
bicategory \M, the analogue of the category of Hopf modules for $A$ is an
Eilenberg-Moore construction for a certain monad in
$\mathbf{Hom}(\M^{\mathrm{op}},\mathbf{Cat})$. We study the existence of the
internalisation of this notion, called the Hopf module construction, by
extending the completion under Eilenberg-Moore objects of a 2-category to a
endo-homomorphism of tricategories on $\mathbf{Bicat}$.
Our main result is the equivalence between the existence of a left
dualization for $A$ ({\em i.e.}, $A$ is left autonomous) and the validity of an
analogue of the structure theorem of Hopf modules. In this case the Hopf module
construction for $A$ always exists.
We use these results to study the lax centre of a left autonomous map
pseudomonoid. We show that the lax centre is the Eilenberg-Moore construction
for a certain monad on $A$ (one existing if the other does). If $A$ is also
right autonomous, then the lax centre equals the centre. We look at the
examples of the bicategories of \V-modules and of comodules in \V, and obtain
the Drinfel'd double of a coquasi-Hopf algebra $H$ as the centre of $H$.
| arxiv topic:math.CT math.QA |
arxiv_dataset-309710.3953 | Strategy for early SUSY searches at ATLAS
hep-ex
The CERN Large Hadron Collider (LHC) is scheduled to commence operation in
2008 and inclusive searches for supersymmetry (SUSY) will be one of our primary
tasks in the first days of LHC operation. It is certain that the final state of
multijets + missing transverse energy will provide a superior performance in
SUSY searches. Strategies to understand the instrumental background and to
understand the Standard Model (SM) background are still under development and
are urgent issues for the coming data. We describe the strategy for early SUSY
searches at the ATLAS experiment using the fist data corresponding to an
integrated luminosity up to 1fb^-1, which comprises much progress in the
data-driven technique for the SM background estimations.
| arxiv topic:hep-ex |
arxiv_dataset-310710.4053 | Crossings and nesting in tangled-diagrams
math.CO math.RT
A tangled-diagram over $[n]=\{1,...,n\}$ is a graph of degree less than two
whose vertices $1,...,n$ are arranged in a horizontal line and whose arcs are
drawn in the upper halfplane with a particular notion of crossings and
nestings. Generalizing the construction of Chen {\it et.al.} we prove a
bijection between generalized vacillating tableaux with less than $k$ rows and
$k$-noncrossing tangled-diagrams and study their crossings and nestings. We
show that the number of $k$-noncrossing and $k$-nonnesting tangled-diagrams are
equal and enumerate tangled-diagrams.
| arxiv topic:math.CO math.RT |
arxiv_dataset-311710.4153 | Quantum Indeterminacy of Emergent Spacetime
gr-qc astro-ph hep-th
It is shown that nearly-flat 3+1D spacetime emerging from a dual quantum
field theory in 2+1D displays quantum fluctuations from classical Euclidean
geometry on macroscopic scales. A covariant holographic mapping is assumed,
where plane wave states with wavevector k on a 2D surface map onto classical
null trajectories in the emergent third dimension at an angle \theta=l_P k
relative to the surface element normal, where l_P denotes the Planck length.
Null trajectories in the 3+1D world then display quantum uncertainty of angular
orientation, with standard deviation \Delta\theta=\sqrt{l_P/z} for longitudinal
propagation distance z in a given frame. The quantum complementarity of
transverse position at macroscopically separated events along null trajectories
corresponds to a geometry that is not completely classical, but displays
observable holographic quantum noise. A statistical estimator of the
fluctuations from Euclidean behavior is given for a simple thought experiment
based on measured sides of triangles. The effect can be viewed as sampling
noise due to the limited degrees of freedom of such a theory, consistent with
covariant bounds on entropy.
| arxiv topic:gr-qc astro-ph hep-th |
arxiv_dataset-312710.4253 | There are non homotopic framed homotopies of long knots
math.GT
Let $\mathcal {M}$ be the space of all, including singular, long knots in
3-space and for which a fixed projection into the plane is an immersion. Let
$cl(\Sigma^{(1)}_{iness})$ be the closure of the union of all singular knots in
$\mathcal {M}$ with exactly one ordinary double point and such that the two
resolutions represent the same (non singular) knot type. We call
$\Sigma^{(1)}_{iness}$ the {\em inessential walls} and we call $\mathcal
{M}_{ess} = \mathcal {M} \setminus cl(\Sigma^{(1)}_{iness})$ the {\em essential
diagram space}. We construct a non trivial class in $H^1(\mathcal {M}_{ess};
\mathbb{Z}[A, A^{-1}])$ by an extension of the Kauffman bracket. This implies
in particular that there are loops in $\mathcal {M}_{ess}$ which consist of
regular isotopies of knots together with crossing changings and which are not
contractible in $\mathcal {M}_{ess}$ (leading to the title of the paper).
We conjecture that our construction gives rise to a new knot polynomial for
knots of unknotting number one.
| arxiv topic:math.GT |
arxiv_dataset-313710.4353 | Reduction to the Simplest - The Complexity of Minimalistic Heteropolymer
Models
cond-mat.soft physics.bio-ph
Simple coarse-grained hydrophobic-polar models for heteropolymers as the
lattice HP and the off-lattice AB model allow a general classification of
characteristic behaviors for hydrophobic-core based tertiary folding. The
strongly reduced computational efforts enable one to reveal systematically the
thermodynamic properties of comparatively long sequences in a wide temperature
range of conformational activity. Based on a suitable cooperativity parameter,
characteristic folding channels and free-energy landscapes, which have strong
similarities with realistic folding paths, can be analysed.
| arxiv topic:cond-mat.soft physics.bio-ph |
arxiv_dataset-314710.4453 | Non-rational configurations, polytopes, and surfaces
math.MG math.CO
It is an amazing and a bit counter-intuitive discovery by Micha Perles from
the sixties that there are ``non-rational polytopes'': combinatorial types of
convex polytopes that cannot be realized with rational vertex coordinates.
We describe a simple construction of non-rational polytopes that does not
need duality (Perles' ``Gale diagrams''): It starts from a non-rational point
configuration in the plane, and proceeds with so-called Lawrence extensions.
We also show that there are non-rational polyhedral surfaces in 3-space, a
discovery by Ulrich Brehm from 1997. His construction also starts from any
non-rational point configuration in the plane, and then performs what one
should call Brehm extensions, in order to obtain non-rational partial surfaces.
These examples and objects are first mile stones on the way to the remarkable
"universality theorems'' for polytopes and for polyhedral surfaces by Mn\"ev
(1986), Richter-Gebert (1994), and Brehm (1997).
| arxiv topic:math.MG math.CO |
arxiv_dataset-315710.4553 | Diffuse UV light associated with the Spiderweb Galaxy: evidence for
in-situ star formation outside galaxies
astro-ph
We present detailed images of diffuse UV intergalactic light (IGL), situated
in a 60kpc halo that surrounds the radio galaxy MRC 1138-262 at z=2. We discuss
the nature of the IGL and rule out faint cluster galaxies, nebular continuum
emission, synchrotron, inverse Compton emission and scattering of galactic
stellar light as possible sources of the IGL. Dust scattered quasar light is an
unlikely possibility that cannot be ruled out entirely. We conclude that the
source of the IGL is most likely to be a young stellar population distributed
in a halo encompassing the radio and satellite galaxies, undergoing star
formation at a rate greater than 57 Msun/yr. Within 70kpc of the radio core,
approximately 44% of the star formation that is traced by UV light occurs in
this diffuse mode. The average UV colour of the IGL is bluer than the average
galaxy colour, and there is a trend for the IGL to become bluer with increasing
radius from the radio galaxy. Both the galaxies and the IGL show a UV
colour--surface brightness relation which can be obtained by variations in
either stellar population age or extinction. These observations show a
different, but potentially important mode of star formation, that is diffuse in
nature. Star formation, as traced by UV light, occurs in two modes in the high
redshift universe: one in the usual Lyman break galaxy clump-like mode on kpc
scales, and the other in a diffuse mode over a large region surrounding massive
growing galaxies. Such a mode of star formation can easily be missed by high
angular resolution observations that are well suited for detecting high surface
brightness compact galaxies. Extrapolating from these results, it is possible
that a significant amount of star formation occurs in large extended regions
within the halos of the most massive galaxies forming at high redshift.
| arxiv topic:astro-ph |
arxiv_dataset-316710.4653 | Simultaneous Reduction of Dynamic and Static Power in Scan Structures
cs.AR
Power dissipation during test is a major challenge in testing integrated
circuits. Dynamic power has been the dominant part of power dissipation in CMOS
circuits, however, in future technologies the static portion of power
dissipation will outreach the dynamic portion. This paper proposes an efficient
technique to reduce both dynamic and static power dissipation in scan
structures. Scan cell outputs which are not on the critical path(s) are
multiplexed to fixed values during scan mode. These constant values and primary
inputs are selected such that the transitions occurred on non-multiplexed scan
cells are suppressed and the leakage current during scan mode is decreased. A
method for finding these vectors is also proposed. Effectiveness of this
technique is proved by experiments performed on ISCAS89 benchmark circuits.
| arxiv topic:cs.AR |
arxiv_dataset-317710.4753 | Verifying Safety-Critical Timing and Memory-Usage Properties of Embedded
Software by Abstract Interpretation
cs.LO
Static program analysis by abstract interpretation is an efficient method to
determine properties of embedded software. One example is value analysis, which
determines the values stored in the processor registers. Its results are used
as input to more advanced analyses, which ultimately yield information about
the stack usage and the timing behavior of embedded software.
| arxiv topic:cs.LO |
arxiv_dataset-318710.4853 | Erratum: Propagation Effects on the Breakdown of a Linear Amplifier
Model: Complex-Mass Schrodinger Equation Driven by the Square of a Gaussian
Field
math-ph math.MP
The proof of the inequality $\lambda_{q}(x,t)\le (q\mu_{x,t} -0^+)^{-1}$ [p
750, below Eq. (29)] is based on the statement that ${\cal E}(x,t;s)$ is an
entire function of $s\in {\mathbb C}^M$ [see below Eq. (30)]. But according to
Equation (9) and Lemma 1, all we know is that ${\cal E}(x,t;s)$ is an entire
function of $k(s)\in {\mathbb R}^N$. Nevertheless, the above inequality holds,
hence the proposition 1.
| arxiv topic:math-ph math.MP |
arxiv_dataset-319710.4953 | Different canonical formulations of Einstein's theory of gravity
gr-qc
We describe the four most famous versions of the classical canonical
formalism in the Einstein theory of gravity: the Arnovitt-Deser-Misner
formalism, the Faddeev-Popov formalism, the tetrad formalism in the usual form,
and the tetrad formalism in the form best suited for constructing the loop
theory of gravity, which is now being developed. We present the canonical
transformations relating these formalisms. The paper is written mainly for
pedagogical purposes.
| arxiv topic:gr-qc |
arxiv_dataset-320710.5053 | Oxygen-isotope effect on the superconducting gap in the cuprate
superconductor Y_{1-x}Pr_xBa_2Cu_3O_{7-\delta}
cond-mat.supr-con
The oxygen-isotope (^{16}O/^{18}O) effect (OIE) on the zero-temperature
superconducting energy gap \Delta_0 was studied for a series of
Y_{1-x}Pr_xBa_2Cu_3O_{7-\delta} samples (0.0\leq x\leq0.45). The OIE on
\Delta_0 was found to scale with the one on the superconducting transition
temperature. These experimental results are in quantitative agreement with
predictions from a polaronic model for cuprate high-temperature superconductors
and rule out approaches based on purely electronic mechanisms.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-321710.5153 | Bounds on long-lived charged massive particles from Big Bang
nucleosynthesis
hep-ph astro-ph
The Big Bang nucleosynthesis (BBN) in the presence of charged massive
particles (CHAMPs) is studied in detail. All currently known effects due to the
existence of bound states between CHAMPs and nuclei, including possible
late-time destruction of Li6 and Li7 are included. The study sets conservative
bounds on CHAMP abundances in the decay time range 3x10^2 sec - 10^12 sec. It
is stressed that the production of Li6 at early times T ~ 10keV is
overestimated by a factor ~ 10 when the approximation of the Saha equation for
the He4 bound state fraction is utilised. To obtain conservative limits on the
abundance of CHAMPs, a Monte-Carlo analysis with ~ 3x10^6 independent BBN runs,
varying reaction rates of nineteen different reactions, is performed (see
attached erratum, however). The analysis yields the surprising result that
except for small areas in the particle parameter space conservative constraints
on the abundance of decaying charged particles are currently very close to
those of neutral particles. It is shown that, in case a number of heretofore
unconsidered reactions may be determined reliably in future, it is conceivable
that the limit on CHAMPs in the early Universe could be tightened by orders of
magnitude. An ERRATUM gives limits on primordial CHAMP densities when the by
Ref. Kamimura et al. recently more accurately determined CHAMP reaction rates
are employed.
| arxiv topic:hep-ph astro-ph |
arxiv_dataset-322710.5253 | Structure of Supergiant Shells in the Large Magellanic Cloud
astro-ph
Nine supergiant shells (SGSs) have been identified in the Large Magellanic
Cloud (LMC) based on H-alpha images, and twenty-three SGSs have been reported
based on HI 21-cm line observations, but these sets do not always identify the
same structures. We have examined the physical structure of the optically
identified SGSs using HI channel maps and P-V diagrams to analyze the gas
kinematics. There is good evidence for seven of the nine optically identified
SGSs to be true shells. Of these seven H-alpha SGSs, four are the ionized inner
walls of HI SGSs, while three are an ionized portion of a larger and more
complex HI structure. All of the H-alpha SGSs are identified as such because
they have OB associations along the periphery or in the center, with younger OB
associations more often found along the periphery. After roughly 12 Myrs, if no
new OB associations have been formed a SGS will cease to be identifiable at
visible wavelengths. Thus, the presence and location of ionizing sources is the
main distinction between shells seen only in HI and those also seen in H-alpha.
Based on our analysis, H-alpha observations alone cannot unambiguously identify
SGSs, especially in distant galaxies.
| arxiv topic:astro-ph |
arxiv_dataset-323710.5353 | Phase-shifts in stochastic resonance in a Chua circuit
nlin.CD
We present an experimental study of stochastic resonance in an electronic
Chua circuit operating in the chaotic regime. We study in detail the
switch-phase distribution and the phase-shift between sinusoidal forcing for
two responses of the circuit: one depending on both inter-well and intra-well
dynamics and the other depending only on inter-well dynamics. We describe the
two relevant de-synchronizatrion mechanisms for high and low frequencies of the
forcing and present a method to detect the optimal noise intensity from switch
phases which coincides with the one derived from the observation of the
signal-to-noise ratio or residence times.
| arxiv topic:nlin.CD |
arxiv_dataset-324710.5453 | Integral elements of K-theory and products of modular curves II
math.NT
We discuss the relationship between different notions of "integrality" in
motivic cohomology/K-theory which arise in the Beilinson and Bloch-Kato
conjectures, and prove their equivalence in some cases for products of curves
(used in the authors' previous paper in this series), as well as obtaining a
general result, first proved by Jannsen (unpublished), which reduces their
equivalence to standard conjectures in arithmetic algebraic geometry.
| arxiv topic:math.NT |
arxiv_dataset-325710.5553 | Probing the photonic local density of states with electron energy loss
spectroscopy
cond-mat.mtrl-sci
Electron energy-loss spectroscopy (EELS) performed in transmission electron
microscopes is shown to directly render the photonic local density of states
(LDOS) with unprecedented spatial resolution, currently below the nanometer.
Two special cases are discussed in detail: (i) 2D photonic structures with the
electrons moving along the translational axis of symmetry and (ii) quasi-planar
plasmonic structures under normal incidence. Nanophotonics in general and
plasmonics in particular should benefit from these results connecting the
unmatched spatial resolution of EELS with its ability to probe basic optical
properties like the photonic LDOS.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-326710.5653 | Time-dependent quasi-Hermitian Hamiltonians and the unitarity of quantum
evolution
quant-ph
We show that the consequences of an introduction of a manifest
time-dependence in a pseudo-Hermitian Hamiltonian H=H(t) are by far less
drastic than suggested by A. Mostafazadeh in Phys. Lett. B 650 (2007) 208
(arXiv:0706.1872v2 [quant-ph]). In particular, the unitarity of the evolution
does not necessitate the time-independence of the metric $\eta_+=\eta_+(t)$.
| arxiv topic:quant-ph |
arxiv_dataset-327710.5753 | Integrability and reduction of Poisson group actions
math.SG math.DG
In this paper we study Poisson actions of complete Poisson groups, without
any connectivity assumption or requiring the existence of a momentum map. For
any complete Poisson group $G$ with dual $G^\star$ we obtain a suitably
connected integrating symplectic double groupoid $\calS$. As a consequence, the
cotangent lift of a Poisson action on an integrable Poisson manifold $P$ can be
integrated to a Poisson action of the symplectic groupoid
$\poidd{\calS}{G^\star}$ on the symplectic groupoid for $P$. Finally, we show
that the quotient Poisson manifold $P/G$ is also integrable, giving an explicit
construction of a symplectic groupoid for it, by a reduction procedure on an
associated morphism of double Lie groupoids.
| arxiv topic:math.SG math.DG |
arxiv_dataset-328710.5853 | Geometric approach towards stable homotopy groups of spheres. Kervaire
Invariant
math.GT math.AT
It is proved that there exists an integer $L$ such that a framed manifold of
dimension $2^l-2$, $l\le L$ has the trivial Kervaire Invariant.
| arxiv topic:math.GT math.AT |
arxiv_dataset-329711.0008 | Positronium-ion decay
hep-ph physics.atom-ph
We present a precise theoretical prediction for the decay width of the bound
state of two electrons and a positron (a negative positronium ion), Gamma(Ps^-)
= 2.087 085(12)/ns. We include O(alpha^2) effects of hard virtual photons as
well as soft corrections to the wave function and the decay amplitude. An
outcome of a large-scale variational calculation, this is the first result for
second-order corrections to a decay of a three-particle bound state. It will be
tested experimentally in the new positronium-ion facility in Garching in
Germany.
| arxiv topic:hep-ph physics.atom-ph |
arxiv_dataset-330711.0108 | On the Exact Matrix Representation for Transverse Magnetic Multiple
Scattering by an Infinite Grating of Insulating Dielectric Circular Cylinders
at Oblique Incidence
math-ph math.MP
A computational algorithm for the exact equations representing the scattering
coefficients of an infinite grating of insulating dielectric circular cylinders
associated with obliquely incident vertically polarized plane electromagnetic
waves is generated by matrix methods, and the solution for the scattering
coefficients is acquired by a matrix inversion procedure.
| arxiv topic:math-ph math.MP |
arxiv_dataset-331711.0208 | Hall Conductivity in a Spin-Triplet Superconductor
cond-mat.supr-con cond-mat.str-el
We calculate the Hall conductivity for a spin-triplet superconductor, using a
generalized pairing symmetry dependent on an arbitrary phase, $\vphi$. A
promising candidate for such an order parameter is Sr$_{2}$RuO$_{4}$, whose
superconducting order parameter symmetry is still subject to investigation. The
value of this phase can be determined through Kerr rotation and DC Hall
conductivity measurements. Our calculations impose significant constraints on
$\vphi$.
| arxiv topic:cond-mat.supr-con cond-mat.str-el |
arxiv_dataset-332711.0308 | The influence of bond-rigidity and cluster diffusion on the
self-diffusion of hard spheres with square-well interaction
cond-mat.soft
Hard spheres interacting through a square-well potential were simulated using
two different methods: Brownian Cluster Dynamics (BCD) and Event Driven
Brownian Dynamics (EDBD). The structure of the equilibrium states obtained by
both methods were compared and found to be almost the identical. Self diffusion
coefficients ($D$) were determined as a function of the interaction strength.
The same values were found using BCD or EDBD. Contrary the EDBD, BCD allows one
to study the effect of bond rigidity and hydrodynamic interaction within the
clusters. When the bonds are flexible the effect of attraction on $D$ is
relatively weak compared to systems with rigid bonds. $D$ increases first with
increasing attraction strength, and then decreases for stronger interaction.
Introducing intra-cluster hydrodynamic interaction weakly increases $D$ for a
given interaction strength. Introducing bond rigidity causes a strong decrease
of $D$ which no longer shows a maximum as function of the attraction strength.
| arxiv topic:cond-mat.soft |
arxiv_dataset-333711.0408 | Hinode observations reveal boundary layers of magnetic elements in the
solar photosphere
astro-ph
We study the structure of the magnetic elements in network-cell interiors. A
quiet Sun area close to the disc centre was observed with the
spectro-polarimeter of the Solar Optical Telescope on board the Hinode space
mission, which yielded the best spatial resolution ever achieved in
polarimetric data of the Fe I 630 nm line pair. For comparison and
interpretation, we synthesize a similar data set from a three-dimensional
magneto-hydrodynamic simulation. We find several examples of magnetic elements,
either roundish (tube) or elongated (sheet), which show a central area of
negative Stokes-V area asymmetry framed or surrounded by a peripheral area with
larger positive asymmetry. This pattern was predicted some eight years ago on
the basis of numerical simulations. Here, we observationally confirm its
existence for the first time. We gather convincing evidence that this pattern
of Stokes-V area asymmetry is caused by the funnel-shaped boundary of magnetic
elements that separates the flux concentration from the weak-field environment.
We also conclude that this kind of magnetic element of the internetwork is
accompanied by electric current sheets.
| arxiv topic:astro-ph |
arxiv_dataset-334711.0508 | A Schur Complement Approach to Chiral Fermions
hep-lat
Lattice chiral fermions are synonymous to the Ginsparg-Wilson relation.
Indeed, this relation is satisfied by the overlap, domain wall and perfect
action fermion kernel.
In a recent work we have shown that it is possible to take a direct RG
approach for fermions in the presence of gauge fields. This is due to an
algebraically implicit blocking technique which yields a Schur-complementary
coarse Dirac operator. Using a Schur complement approximation which is stable
and regular, the scheme can be iterated to the fixed point.
In this talk, we elaborate more on the direct RG approach and show how to get
highly improved chiral fermions on the coarse lattice with the gauge fields
remaining on the fine lattice. We give numerical examples in the case of
lattice QCD using QCDLAB {\tt http://phys.fshn.edu.al/qcdlab.html}
| arxiv topic:hep-lat |
arxiv_dataset-335711.0608 | On Fixed-multiplicity Corrections to Correlators
nucl-th
Correction terms generated in the correlator analysis due to
multiplicity-dependent observable mean are investigated. A procedure for
subtraction of such terms from calculated correlator estimates is suggested and
the obtained results are discussed.
| arxiv topic:nucl-th |
arxiv_dataset-336711.0708 | A Rank-Metric Approach to Error Control in Random Network Coding
cs.IT math.IT
The problem of error control in random linear network coding is addressed
from a matrix perspective that is closely related to the subspace perspective
of K\"otter and Kschischang. A large class of constant-dimension subspace codes
is investigated. It is shown that codes in this class can be easily constructed
from rank-metric codes, while preserving their distance properties. Moreover,
it is shown that minimum distance decoding of such subspace codes can be
reformulated as a generalized decoding problem for rank-metric codes where
partial information about the error is available. This partial information may
be in the form of erasures (knowledge of an error location but not its value)
and deviations (knowledge of an error value but not its location). Taking
erasures and deviations into account (when they occur) strictly increases the
error correction capability of a code: if $\mu$ erasures and $\delta$
deviations occur, then errors of rank $t$ can always be corrected provided that
$2t \leq d - 1 + \mu + \delta$, where $d$ is the minimum rank distance of the
code. For Gabidulin codes, an important family of maximum rank distance codes,
an efficient decoding algorithm is proposed that can properly exploit erasures
and deviations. In a network coding application where $n$ packets of length $M$
over $F_q$ are transmitted, the complexity of the decoding algorithm is given
by $O(dM)$ operations in an extension field $F_{q^n}$.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-337711.0808 | Supernovae in Low-Redshift Galaxy Clusters: Observations by the Wise
Observatory Optical Transient Search (WOOTS)
astro-ph
We describe the Wise Observatory Optical Transient Search (WOOTS), a survey
for supernovae (SNe) and other variable and transient objects in the fields of
redshift 0.06-0.2 Abell galaxy clusters. We present the survey design and
data-analysis procedures, and our object detection and follow-up strategies. We
have obtained follow-up spectroscopy for all viable SN candidates, and present
the resulting SN sample here. Out of the 12 SNe we have discovered, seven are
associated with our target clusters while five are foreground or background
field events. All but one of the SNe (a foreground field event) are Type Ia
SNe. Our non-cluster SN sample is uniquely complete, since all SN candidates
have been either spectroscopically confirmed or ruled out. This allows us to
estimate that flux-limited surveys similar to WOOTS would be dominated (~80%)
by SNe Ia. Our spectroscopic follow-up observations also elucidate the
difficulty in distinguishing active galactic nuclei from SNe. In separate
papers we use the WOOTS sample to derive the SN rate in clusters for this
redshift range, and to measure the fraction of intergalactic cluster SNe. We
also briefly report here on some quasars and asteroids discovered by WOOTS.
| arxiv topic:astro-ph |
arxiv_dataset-338711.0908 | Quasi-invariant and super-coinvariant polynomials for the generalized
symmetric group
math.CO
The aim of this work is to extend the study of super-coinvariant polynomials,
to the case of the generalized symmetric group $G_{n,m}$, defined as the wreath
product $C_m\wr\S_n$ of the symmetric group by the cyclic group. We define a
quasi-symmetrizing action of $G_{n,m}$ on $\Q[x_1,...,x_n]$, analogous to those
defined by Hivert in the case of $\S_n$. The polynomials invariant under this
action are called quasi-invariant, and we define super-coinvariant polynomials
as polynomials orthogonal, with respect to a given scalar product, to the
quasi-invariant polynomials with no constant term. Our main result is the
description of a Gr\"obner basis for the ideal generated by quasi-invariant
polynomials, from which we dedece that the dimension of the space of
super-coinvariant polynomials is equal to $m^n C_n$ where $C_n$ is the $n$-th
Catalan number.
| arxiv topic:math.CO |
arxiv_dataset-339711.1008 | Corner-Impact Bifurcations: a novel class of discontinuity-induced
bifurcations in Cam-Follower Systems
math-ph math.MP
This paper is concerned with the analysis of a class of impacting systems of
relevance in applications: cam-follower systems. We show that these systems,
which can be modelled as discontinuously forced impact oscillators, can exhibit
complex behaviour due to the detachment at high rotational speeds between the
follower and the cam. We propose that the observed phenomena can be explained
in terms of a novel type of discontinuity-induced bifurcation, termed as
corner-impact. We present a complete analysis of this bifurcation in the case
of non-autonomous impact oscillator and explain the transition to chaos
observed in a representative cam-follower example. The theoretical findings are
validated numerically.
| arxiv topic:math-ph math.MP |
arxiv_dataset-340711.1108 | Evolution of convex lens-shaped networks under curve shortening flow
math.DG math.AP
We consider convex symmetric lens-shaped networks in R^2 that evolve under
curve shortening flow. We show that the enclosed convex domain shrinks to a
point in finite time. Furthermore, after appropriate rescaling the evolving
networks converge to a self-similarly shrinking network, which we prove to be
unique in an appropriate class. We also include a classification result for
some self-similarly shrinking networks.
| arxiv topic:math.DG math.AP |
arxiv_dataset-341711.1208 | Finite dimensional subspaces of noncommutative $L_p$ spaces
math.FA math.OA
We prove the following noncommutative version of Lewis's classical result.
Every n-dimensional subspace E of Lp(M) (1<p<\infty) for a von Neumann algebra
M satisfies d_{cb}(E, RC^n_{p'}) \leq c_p n^{\abs{1/2-1/p}} for some constant
c_p depending only on $p$, where $1/p +1/p' =1$ and $RC^n_{p'} = [R_n\cap C_n,
R_n+C_n]_{1/p'}$. Moreover, there is a projection $P:Lp(M) --> Lp(M)$ onto E
with $\norm{P}_{cb} \leq c_p n^{\abs{1/2-1/p}}.$ We follow the classical change
of density argument with appropriate noncommutative variations in addition to
the opposite trick.
| arxiv topic:math.FA math.OA |
arxiv_dataset-342711.1308 | E(5) and X(5) shape phase transitions within a Skyrme Hartree-Fock + BCS
approach
nucl-th
Self-consistent Skyrme Hartree-Fock plus BCS calculations are performed to
generate potential energy curves (PEC) in various chains of Pd, Xe, Ba, Nd, Sm,
Gd, and Dy isotopes. The evolution of shapes with the number of nucleons is
studied in a search for signatures of E(5) and X(5) critical point symmetries.
It is shown that the energy barriers in the PECs are determined to a large
extent by the treatment of the pairing correlations.
| arxiv topic:nucl-th |
arxiv_dataset-343711.1408 | Particle-number conservation in static-path approximation for thermal
superfluid systems
nucl-th
By applying particle-number projection to the static-path approximation
(SPA), the heat capacity and the breakdown of pairing correlations are
investigated in the thermally excited, superfluid systems 172Yb, 94Mo, and
56Fe. For the heavy nucleus 172Yb, the heat capacities in both the SPA and the
number-projected SPA (NPSPA) exhibit an S shape; the difference between the SPA
and NPSPA heat-capacity curves is not very large and the particle-number
projection thereby enhances the S shape already seen in the SPA. The
temperature at which the S-shape of heat capacity curve occurs parallels the
temperature of the breakdown of pairing correlations as indicated by the
effective pairing gap. However, for the comparatively lighter nuclei 94Mo and
56Fe, the SPA does not produce an S-shaped heat capacity on its own; only after
particle-number projection the S shape appears in the heat-capacity curve. For
94Mo, we compare the NPSPA result with thermal odd-even mass differences, which
are regarded as a direct measure of the pairing gap.
| arxiv topic:nucl-th |
arxiv_dataset-344711.1508 | Aharonov-Bohm effect in graphene
cond-mat.mes-hall
We investigate experimentally transport through ring-shaped devices etched in
graphene and observe clear Aharonov-Bohm conductance oscillations. The
temperature dependence of the oscillation amplitude indicates that below 1 K
the phase coherence length is comparable to or larger than the size of the
ring. An increase in the amplitude is observed at high magnetic field, when the
cyclotron diameter becomes comparable to the width of the arms of the ring. By
measuring the dependence on gate voltage, we also observe an unexpected linear
dependence of the oscillation amplitude on the ring conductance, which had not
been reported earlier in rings made using conventional metals or semiconducting
heterostructures.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-345711.1608 | In Ehresmann's footsteps: from Group Geometries to Groupoid Geometries
math.DG math.CT
For a smooth (locally trivial) principal bundle in Ehresmann's sense, the
relation between the commuting vertical and horizontal actions of the
structural Lie group and the structural Lie groupoid (isomorphisms between
vertical fibers) is regarded as a special case of a symmetrical concept of
conjugation between "principal" Lie groupoid actions, allowing possibly
non-locally trivial bundles. A diagrammatic description of this concept via a
symmetric "butterfly diagram" allows its "internalization" in a wide class of
categories (used by "working mathematicians") whenever they are endowed with
two distinguished classes of monomorphisms and epimorphisms mimicking the
properties of embeddings and surjective submersions. As an application, a
general theorem of "universal activation" encompasses in a unified way such
various situations as Palais' theory of globalization for partial action laws,
the realization of non-abelian cocycles (including Haefliger cocycles for
foliations) or the description of the "homogeneous space" attached to an
embedding of Lie groups (still valid for Lie groupoids).
| arxiv topic:math.DG math.CT |
arxiv_dataset-346711.1708 | Axion as a CDM component
hep-ph astro-ph hep-th
I discuss the essential features of the QCD axion: the strong CP solution and
hence its theoretical necessity. I also review the effects of the QCD axion on
astrophysics and cosmology, in particular with emphasis on its role in the dark
matter component together with its supersymmetric partner axino. It is pointed
out that string theory may or may not give a detectable QCD axion.
| arxiv topic:hep-ph astro-ph hep-th |
arxiv_dataset-347711.1808 | Cross-Kerr effective Hamiltonian for a non-resonant four-level atom
quant-ph
We derive a cross-Kerr type effective Hamiltonian for the four-level atom
interacting with three electromagnetic fields in the N-configuration. When the
atom has relaxed into the ground state a cross-Kerr nonlinearity arises between
two weak probe fields. As a development on earlier work we show in general that
the atom will also display a linear and self-Kerr response. However, if certain
resonance conditions are satisfied then the linear and self-Kerr interactions
will vanish. The electrical susceptibilities of the probe transitions are also
explored and it is shown that a large, pure cross-Kerr nonlinearity can be
generated with vanishing absorption of both probe fields.
| arxiv topic:quant-ph |
arxiv_dataset-348711.1908 | Scaling functions applied to three-body recombination of Cesium-133
atoms
cond-mat.other nucl-th
We demonstrate the implications of Efimov physics in the recently measured
recombination rate of Cesium-133 atoms. By employing previously calculated
results for the energy dependence of the recombination rate of Helium-4 atoms,
we obtain three independent scaling functions that are capable of describing
the recombination rates over a large energy range for identical bosons with
large scattering length. We benchmark these and previously obtained scaling
functions by successfully comparing their predictions with full atom-dimer
phase shift calculations with artificial Helium-4 potentials yielding large
scattering lengths. Exploiting universality, we finally use these functions to
determine the 3-body recombination rate of Cesium-133 atoms with large positive
scattering length, compare our results to experimental data obtained by the
Innsbruck group and find excellent agreement.
| arxiv topic:cond-mat.other nucl-th |
arxiv_dataset-349711.2008 | Analytic vectors in continuous p-adic representations
math.RT math.NT
Given a compact p-adic Lie group G over a finite unramified extension L/Q_p
let G_0 be the product over all Galois conjugates of G. We construct an exact
and faithful functor from admissible G-Banach space representations to
admissible locally L-analytic G_0-representations that coincides with passage
to analytic vectors in case L=Q_p. On the other hand, we study the functor
"passage to analytic vectors" and its derived functors over general basefields.
As an application we determine the higher analytic vectors in certain locally
analytic induced representations.
| arxiv topic:math.RT math.NT |
arxiv_dataset-350711.2108 | The Effective Action of N=8 Supergravity
hep-th
We present a simple form of the on-shell gauge-invariant 1-loop effective
action of N=8 supergravity which is manifestly N=8 supersymmetric at the linear
level. By generalizing the dimensional arguments in superspace to non-local
invariants, we show that the 1-loop effective action does not contain any
contributions from bubble and triangle diagrams. The absence of bubbles implies
the absence of conformal and axial anomalies. We also show that the 1-loop
effective action of N=8 supergravity features a "dual" conformal symmetry in
the momentum space.
| arxiv topic:hep-th |
arxiv_dataset-351711.2208 | One Hub-One Process: A Tool Based View on Regulatory Network Topology
q-bio.MN cond-mat.soft
The relationship between the regulatory design and the functionality of
molecular networks is a key issue in biology. Modules and motifs have been
associated to various cellular processes, thereby providing anecdotal evidence
for performance based localization on molecular networks. To quantify
structure-function relationship we investigate similarities of proteins which
are close in the regulatory network of the yeast Saccharomyces Cerevisiae. We
find that the topology of the regulatory network show weak remnants of its
history of network reorganizations, but strong features of co-regulated
proteins associated to similar tasks. This suggests that local topological
features of regulatory networks, including broad degree distributions, emerge
as an implicit result of matching a number of needed processes to a finite
toolbox of proteins.
| arxiv topic:q-bio.MN cond-mat.soft |
arxiv_dataset-352711.2308 | Metal Absorption Systems in Spectra of Pairs of QSOs
astro-ph
We present the first large sample of absorption systems in paired QSOs
consisting of 691 absorption systems in the spectra of 310 QSOs including 170
pairings. All these absorption systems have metal lines, usually C IV or Mg II.
We see 17 cases of absorption in one line-of-sight within 200 km/s (1 Mpc) of
absorption in the paired line-of-sight with the probability at least approx 50%
at 100kpc, declining rapidly to 23% at 100 - 200 kpc. We detect clustering on
0.5Mpc scales and see a hint of the "fingers of God" redshift-space distortion.
The distribution matches absorbers arising in galaxies at z=2 with a normal
correlation function and systematic infall velocities but unusually low random
pair-wise velocity differences. Absorption in gas flowing out from galaxies at
a mean velocity of 250 km/s would produce vastly more elongation than we see.
The UV absorption from fast winds that Adelberger et al. 2005 see in spectra of
LBGs is not representative of the absorption that we see. Either the winds are
confined to LBGs, or they can not extend to 40 kpc with large velocities, while
continuing to make UV absorption we see, implying most metals were in place in
the IGM long before z=2. Separately, when we examine the absorption seen when a
sight line passes a second QSO, we see 19 absorbers within 400 km/s of the
partner QSO. The probability of seeing absorption is approximately constant for
impact parameters 0.1 - 1.5 Mpc. Perhaps we do not see a rapid rise in the
probability at small impact parameters because the UV from QSOs destroys some
absorbers near to the QSOs. The 3D distribution of 64 absorbers around 313 QSOs
is to first order isotropic, with just a hint of the anisotropy expected if the
QSO UV emission is beamed, or alternatively QSOs might emit UV isotropically
but for a surprisingly short time of only 0.3Myr.
| arxiv topic:astro-ph |
arxiv_dataset-353711.2408 | Travelling waves for the Gross-Pitaevskii equation II
math.AP
The purpose of this paper is to provide a rigorous mathematical proof of the
existence of travelling wave solutions to the Gross-Pitaevskii equation in
dimensions two and three. Our arguments, based on minimization under
constraints, yield a full branch of solutions, and extend earlier results,
where only a part of the branch was built. In dimension three, we also show
that there are no travelling wave solutions of small energy.
| arxiv topic:math.AP |
arxiv_dataset-354711.2508 | Finding Planets Around White Dwarf Remnants of Massive Stars
astro-ph
Planet frequency shows a strong positive correlation with host mass from the
hydrogen-burning limit to M ~ 2Msun. No search has yet been conducted for
planets of higher-mass hosts because all existing techniques are insensitive to
these planets. We show that infrared observations of the white-dwarf (WD)
remnants of massive stars 3Msun < M < 7Msun would be sensitive to these planets
for reasons that are closely connected to the insensitivity of other methods.
We identify 49 reasonably bright, young, massive WDs from the Palomar-Green
survey and discuss methods for detecting planets and for distinguishing between
planet and disk explanations for any excess flux observed. The young, bright,
massive WD sample could be expanded by a factor 4-5 by surveying the remainder
of the sky for bright UV-excess objects.
| arxiv topic:astro-ph |
arxiv_dataset-355711.2608 | Expressions of algebra elements and transcendental noncommutative
calculus
math.QA
Ideas from deformation quantization are applied to deform the expression of
elements of an algebra. Extending these ideas to certain transcendental
elements implies that $\frac{1}{i\h}uv$ in the Weyl algebra is naturally viewed
as an indeterminate living in a discrete set $\mathbb{N}{+}{1/2}$ {\it or}
${-}(\mathbb{N}{+}{1/2})$ . This may yield a more mathematical understanding of
Dirac's positron theory.
| arxiv topic:math.QA |
arxiv_dataset-356711.2708 | Global exploration of the energy landscape of solids on the ab initio
level
cond-mat.mtrl-sci
Predicting which crystalline modifications can be present in a chemical
system requires the global exploration of its energy landscape. Due to the
large computational effort involved, in the past this search for sufficiently
stable minima has been performed employing a variety of empirical potentials
and cost functions followed by a local optimization on the ab initio level.
However, this entails the risk of overlooking important modifications that are
not modeled accurately using empirical potentials. In order to overcome this
critical limitation, we develop an approach to employ ab initio energy
functions during the global optimization phase of the structure prediction. As
an example, we perform a global exploration of the landscape of LiF on the ab
initio level and show that the relevant crystalline modifications are found
during the search.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-357711.2808 | The growth at infinity of a sequence of entire functions of bounded
orders
math.CV
In this paper we shall consider the growth at infinity of a sequence $(P_n)$
of entire functions of bounded orders. Our results extend the results in
\cite{trong-tuyen2} for the growth of entire functions of genus zero. Given a
sequence of entire functions of bounded orders $P_n(z)$, we found a nearly
optimal condition, given in terms of zeros of $P_n$, for which $(k_n)$ that we
have \begin{eqnarray*} \limsup_{n\to\infty}|P_n(z)|^{1/k_n}\leq 1
\end{eqnarray*} for all $z\in \mathbb C$ (see Theorem \ref{theo5}). Exploring
the growth of a sequence of entire functions of bounded orders lead naturally
to an extremal function which is similar to the Siciak's extremal function (See
Section 6).
| arxiv topic:math.CV |
arxiv_dataset-358711.2908 | Probing new physics with long-lived charged particles produced by
atmospheric and astrophysical neutrinos
hep-ph astro-ph
As suggested by some extensions of the Standard Model of particle physics,
dark matter may be a super-weakly interacting lightest stable particle, while
the next-to-lightest particle (NLP) is charged and meta-stable. One could test
such a possibility with neutrino telescopes, by detecting the charged NLPs
produced in high-energy neutrino collisions with Earth matter. We study the
production of charged NLPs by both atmospheric and astrophysical neutrinos;
only the latter, which is largely uncertain and has not been detected yet, was
the focus of previous studies. We compute the resulting fluxes of the charged
NLPs, compare those of different origins, and analyze the dependence on the
underlying particle physics setup. We point out that even if the astrophysical
neutrino flux is very small, atmospheric neutrinos, especially those from the
prompt decay of charmed mesons, may provide a detectable flux of NLP pairs at
neutrino telescopes such as IceCube. We also comment on the flux of charged
NLPs expected from proton-nucleon collisions, and show that, for theoretically
motivated and phenomenologically viable models, it is typically sub-dominant
and below detectable rates.
| arxiv topic:hep-ph astro-ph |
arxiv_dataset-359711.3008 | The Galactic Positron Annihilation Radiation & The Propagation of
Positrons in the Interstellar Medium
astro-ph
We consider positron propagation in the interstellar medium and show that the
positrons from the beta-plus decay chains of the radioactive nuclei Ni-56,
Ti-44, and Al-26, produced in Galactic supernovae, can fully account for all
the features of the diffuse Galactic 511 keV annihilation radiation observed by
INTEGRAL/SPI. We also predict additional measurable features that can further
test the origin of positrons and provide new information on the nature of the
interstellar medium.
| arxiv topic:astro-ph |
arxiv_dataset-360711.3108 | A Uniqueness and Periodicity Result for Solutions of Elliptic Equations
in Unbounded Domains
math.AP
We proof a uniqueness and periodicity theorem for bounded solutions of
uniformly elliptic equations in certain unbounded domains.
| arxiv topic:math.AP |
arxiv_dataset-361711.3208 | The Riemann-Hilbert approach to double scaling limit of random matrix
eigenvalues near the "birth of a cut" transition
math-ph math.MP
In this paper we studied the double scaling limit of a random unitary matrix
ensemble near a singular point where a new cut is emerging from the support of
the equilibrium measure. We obtained the asymptotic of the correlation kernel
by using the Riemann-Hilbert approach. We have shown that the kernel near the
critical point is given by the correlation kernel of a random unitary matrix
ensemble with weight $e^{-x^{2\nu}}$. This provides a rigorous proof of the
previous results of Eynard.
| arxiv topic:math-ph math.MP |
arxiv_dataset-362711.3308 | Non Linear Techniques for Increasing Harvesting Energy from
Piezoelectric and Electromagnetic Micro-Power-Generators
cs.OH
Non-linear techniques are used to optimize the harvested energy from
piezoelectric and electromagnetic generators. This paper introduces an
analytical study for the voltage amplification obtained from these techniques.
The analytical study is experimentally validated using a macro model of
piezoelectric generator. Moreover, the integration influences on these
techniques is studied. Through all the obtained results, a suitable structure
for autonomous microsystems is proposed.
| arxiv topic:cs.OH |
arxiv_dataset-363711.3408 | New connection formulae for some q-orthogonal polynomials in q-Askey
scheme
hep-th math-ph math.MP
New nonlinear connection formulae of the q-orthogonal polynomials, such
continuous q-Laguerre, continuous big q-Hermite, q-Meixner-Pollaczek and
q-Gegenbauer polynomials, in terms of their respective classical analogues are
obtained using a special realization of the q-exponential function as infinite
multiplicative series of ordinary exponential function.
| arxiv topic:hep-th math-ph math.MP |
arxiv_dataset-364711.3508 | Explicit Ramsey graphs and Erdos distance problem over finite Euclidean
and non-Euclidean spaces
math.CO
We study the Erdos distance problem over finite Euclidean and non-Euclidean
spaces. Our main tools are graphs associated to finite Euclidean and
non-Euclidean spaces that are considered in Bannai-Shimabukuro-Tanaka (2004,
2007). These graphs are shown to be asymptotically Ramanujan graphs. The
advantage of using these graphs is twofold. First, we can derive new lower
bounds on the Erdos distance problems with explicit constants. Second, we can
construct many explicit tough Ramsey graphs R(3,k).
| arxiv topic:math.CO |
arxiv_dataset-365711.3608 | Quantum Benchmark for Teleportation and Storage of Squeezed States
quant-ph
We provide a quantum benchmark for teleportation and storage of single-mode
squeezed states with zero displacement and a completely unknown degree of
squeezing along a given direction. For pure squeezed input states, a fidelity
higher than 81.5% has to be attained in order to outperform any classical
strategy based on an estimation of the unknown squeezing and repreparation of
squeezed states. For squeezed thermal input states, we derive an upper and a
lower bound on the classical average fidelity which tighten for moderate degree
of mixedness. These results enable a critical discussion of recent experiments
with squeezed light.
| arxiv topic:quant-ph |
arxiv_dataset-366711.3708 | Equations in a free group. Elementary theory
math.GM
We prove the decidability of the elementary theory of a free group.
| arxiv topic:math.GM |
arxiv_dataset-367711.3808 | Hyperfinite graph limits
math.PR math.CO
G\'abor Elek introduced the notion of a hyperfinite graph family: a
collection of graphs is hypefinite if for every $\epsilon>0$ there is some
finite $k$ such that each graph $G$ in the collection can be broken into
connected components of size at most $k$ by removing a set of edges of size at
most $\epsilon|V(G)|$. We presently extend this notion to a certain
compactification of finite bounded-degree graphs, and show that if a sequence
of finite graphs converges to a hyperfinite limit, then the sequence itself is
hyperfinite.
| arxiv topic:math.PR math.CO |
arxiv_dataset-368711.3908 | Mass and Gas Profiles in A1689: Joint X-ray and Lensing Analysis
astro-ph
We carry out a comprehensive joint analysis of high quality HST/ACS and
Chandra measurements of A1689, from which we derive mass, temperature, X-ray
emission and abundance profiles. The X-ray emission is smooth and symmetric,
and the lensing mass is centrally concentrated indicating a relaxed cluster.
Assuming hydrostatic equilibrium we deduce a 3D mass profile that agrees
simultaneously with both the lensing and X-ray measurements. However, the
projected temperature profile predicted with this 3D mass profile exceeds the
observed temperature by ~30% at all radii, a level of discrepancy comparable to
the level found for other relaxed clusters. This result may support recent
suggestions from hydrodynamical simulations that denser, more X-ray luminous
small-scale structure can bias observed temperature measurements downward at
about the same (~30%) level. We determine the gas entropy at 0.1r_{vir} (where
r_{vir} is the virial radius) to be ~800 keV cm^2, as expected for a high
temperature cluster, but its profile at >0.1r_{vir} has a power-law form with
index ~0.8, considerably shallower than the ~1.1 index advocated by theoretical
studies and simulations. Moreover, if a constant entropy ''floor'' exists at
all, then it is within a small region in the inner core, r<0.02r_{vir}, in
accord with previous theoretical studies of massive clusters.
| arxiv topic:astro-ph |
arxiv_dataset-369711.4008 | Weighing Wimps with Kinks at Colliders: Invisible Particle Mass
Measurements from Endpoints
hep-ph
We consider the application of endpoint techniques to the problem of mass
determination for new particles produced at a hadron collider, where these
particles decay to an invisible particle of unknown mass and one or more
visible particles of known mass. We also consider decays of these types for
pair-produced particles and in each case consider situations both with and
without initial state radiation. We prove that, in most (but not all) cases,
the endpoint of an appropriate transverse mass observable, considered as a
function of the unknown mass of the invisible particle, has a kink at the true
value of the invisible particle mass. The co-ordinates of the kink yield the
masses of the decaying particle and the invisible particle. We discuss the
prospects for implementing this method at the LHC.
| arxiv topic:hep-ph |
arxiv_dataset-370711.4108 | Tachyon-Free Non-Supersymmetric Strings on Orbifolds
hep-th
We discuss tachyon-free examples of (Type IIB on) non-compact
non-supersymmetric orbifolds. Tachyons are projected out by discrete torsion
between orbifold twists, while supersymmetry is broken by a Scherk-Schwarz
phase (+1/-1 when acting on space-time bosons/fermions) accompanying some even
order twists. The absence of tachyons is encouraging for constructing
non-supersymmetric D3-brane gauge theories with stable infrared fixed points.
The D3-brane gauge theories in our orbifold backgrounds have chiral N = 1
supersymmetric spectra, but non-supersymmetric interactions.
| arxiv topic:hep-th |
arxiv_dataset-371711.4208 | Towards Structural Classification of Proteins based on Contact Map
Overlap
q-bio.QM
A multitude of measures have been proposed to quantify the similarity between
protein 3-D structure. Among these measures, contact map overlap (CMO)
maximization deserved sustained attention during past decade because it offers
a fine estimation of the natural homology relation between proteins. Despite
this large involvement of the bioinformatics and computer science community,
the performance of known algorithms remains modest. Due to the complexity of
the problem, they got stuck on relatively small instances and are not
applicable for large scale comparison. This paper offers a clear improvement
over past methods in this respect. We present a new integer programming model
for CMO and propose an exact B &B algorithm with bounds computed by solving
Lagrangian relaxation. The efficiency of the approach is demonstrated on a
popular small benchmark (Skolnick set, 40 domains). On this set our algorithm
significantly outperforms the best existing exact algorithms, and yet provides
lower and upper bounds of better quality. Some hard CMO instances have been
solved for the first time and within reasonable time limits. From the values of
the running time and the relative gap (relative difference between upper and
lower bounds), we obtained the right classification for this test. These
encouraging result led us to design a harder benchmark to better assess the
classification capability of our approach. We constructed a large scale set of
300 protein domains (a subset of ASTRAL database) that we have called Proteus
300. Using the relative gap of any of the 44850 couples as a similarity
measure, we obtained a classification in very good agreement with SCOP. Our
algorithm provides thus a powerful classification tool for large structure
databases.
| arxiv topic:q-bio.QM |
arxiv_dataset-372711.4308 | N-particle scattering matrix for electrons interacting on a quantum dot
cond-mat.mes-hall cond-mat.str-el
We present a non-perturbative expression for the scattering matrix of $N$
particles interacting inside a quantum dot. Characterizing the dot by its
resonances, we find a compact form for the scattering matrix in a real-time
representation. We study the transmission probabilities and interaction-induced
orbital entanglement of two electrons incident on the dot in a spin-singlet
state.
| arxiv topic:cond-mat.mes-hall cond-mat.str-el |
arxiv_dataset-373711.4408 | BZ-MC-BP Model for Jet Production from Black Hole Accretion Disc
astro-ph
Three energy mechanisms invoking large-scale magnetic fields are incorporated
in a model to interpret jet production in black hole (BH) systems, i.e., the
Blandford-Znajek (BZ), the magnetic coupling (MC) and Blandford-Payne (BP)
processes. These energy mechanisms can coexist in BH accretion disc based on
the magnetic field configurations constrained by the screw instability,
provided that the BH spin and the power-law index indicating the variation of
the magnetic field at an accretion disc are greater than some critical values.
In this model the jets are driven by the BZ process in the Poynting flux regime
and by the BP process in the hydromagnetic regime, being consistent with the
spine/sheath jet structure observed in BH sources of stellar and supermassive
size.
| arxiv topic:astro-ph |
arxiv_dataset-374711.4508 | Representation and Measure of Structural Information
cs.CC cs.CV cs.IT math.IT
We introduce a uniform representation of general objects that captures the
regularities with respect to their structure. It allows a representation of a
general class of objects including geometric patterns and images in a sparse,
modular, hierarchical, and recursive manner. The representation can exploit any
computable regularity in objects to compactly describe them, while also being
capable of representing random objects as raw data. A set of rules uniformly
dictates the interpretation of the representation into raw signal, which makes
it possible to ask what pattern a given raw signal contains. Also, it allows
simple separation of the information that we wish to ignore from that which we
measure, by using a set of maps to delineate the a priori parts of the objects,
leaving only the information in the structure.
Using the representation, we introduce a measure of information in general
objects relative to structures defined by the set of maps. We point out that
the common prescription of encoding objects by strings to use Kolmogorov
complexity is meaningless when, as often is the case, the encoding is not
specified in any way other than that it exists. Noting this, we define the
measure directly in terms of the structures of the spaces in which the objects
reside. As a result, the measure is defined relative to a set of maps that
characterize the structures. It turns out that the measure is equivalent to
Kolmogorov complexity when it is defined relative to the maps characterizing
the structure of natural numbers. Thus, the formulation gives the larger class
of objects a meaningful measure of information that generalizes Kolmogorov
complexity.
| arxiv topic:cs.CC cs.CV cs.IT math.IT |
arxiv_dataset-375711.4608 | Spin Transfer Torques
cond-mat.other
This tutorial article introduces the physics of spin transfer torques in
magnetic devices. We provide an elementary discussion of the mechanism of spin
transfer torque, and review the theoretical and experimental progress in this
field. Our intention is to be accessible to beginning graduate students. This
is the introductory paper for a cluster of "Current Perspectives" articles on
spin transfer torques published in volume 320 of the Journal of Magnetism and
Magnetic Materials. This article is meant to set the stage for the others which
follow it in this cluster; they focus in more depth on particularly interesting
aspects of spin-torque physics and highlight unanswered questions that might be
productive topics for future research.
| arxiv topic:cond-mat.other |
arxiv_dataset-376711.4708 | On the theory of resonances in non-relativistic QED and related models
math-ph math.MP
We study the mathematical theory of quantum resonances in the standard model
of non-relativistic QED and in Nelson's model. In particular, we estimate the
survival probability of metastable states corresponding to quantum resonances
and relate the resonances to poles of an analytic continuation of matrix
elements of the resolvent of the quantum Hamiltonian.
| arxiv topic:math-ph math.MP |
arxiv_dataset-377711.4808 | The MAJORANA 76Ge neutrino less double-beta decay project: A brief
update
nucl-ex
At present, MAJORANA is a research and development (R&D) project to
investigate the feasibility and cost of constructing and operating a one ton
decay experiment with ~1000 kg of Ge detectors fabricated from germanium
enriched to 86% in . The study will include three separate cryostats with
various types of detectors: un-segmented, un-segmented point-contact, minimally
segmented, and highly segmented. One cryostat will contain at least 30 kg of
enriched (preferably point-contact) detectors. The performance of the cryostats
and detectors as well as background levels will be investigated. The goal of
the demonstrator project is to reach a discovery sensitivity of ~ 1026 y.
| arxiv topic:nucl-ex |
arxiv_dataset-378711.4908 | Zeeman split lines in CP stars: a discovery of low-contrast fields in
slow rotators?
astro-ph
We show that high-resolution observations of resolved Zeeman split lines can
be used to obtain new constraints on the stellar magnetic field geometry. In
particular, the contrast of the field strength distribution over the stellar
surface can be deduced from the differential measurement of the second moment
of the pi and sigma Zeeman components. Our analysis of the triplet lines in
slowly rotating cool magnetic CP stars uncovers a surprisingly homogeneous
field structure, inconsistent with any low-order multipolar geometry.
| arxiv topic:astro-ph |
arxiv_dataset-379711.5008 | Smoothness criteria for Navier-Stokes equations in terms of regularity
along the steam lines
math.AP
This article is devoted to a regularity criteria for solutions of the
Navier-Stokes equations in terms of regularity along the stream lines. More
precisely, we prove that a suitable weak solution for the Navier-Stokes
equations is regular under some constraint on the second derivative of |u|
along the stream lines.
| arxiv topic:math.AP |
arxiv_dataset-380712.0079 | Non-Oberbeck-Boussinesq effects in turbulent thermal convection in
ethane close to the critical point
physics.flu-dyn
As shown in earlier work (Ahlers et al., J. Fluid Mech. 569, p.409 (2006)),
non-Oberbeck Boussinesq (NOB) corrections to the center temperature in
turbulent Rayleigh-Benard convection in water and also in glycerol are governed
by the temperature dependences of the kinematic viscosity and the thermal
diffusion coefficient. If the working fluid is ethane close to the critical
point the origin of non-Oberbeck-Boussinesq corrections is very different, as
will be shown in the present paper. Namely, the main origin of NOB corrections
then lies in the strong temperature dependence of the isobaric thermal
expansion coefficient \beta(T). More precisely, it is the nonlinear
T-dependence of the density \rho(T) in the buoyancy force which causes another
type of NOB effect. We demonstrate that through a combination of experimental,
numerical, and theoretical work, the latter in the framework of the extended
Prandtl-Blasius boundary layer theory developed in Ahlers et al., J. Fluid
Mech. 569, p.409 (2006). The latter comes to its limits, if the temperature
dependence of the thermal expension coefficient \beta(T) is significant.
| arxiv topic:physics.flu-dyn |
arxiv_dataset-381712.0179 | Rates of convergence for minimal distances in the central limit theorem
under projective criteria
math.ST math.PR stat.TH
In this paper, we give estimates of ideal or minimal distances between the
distribution of the normalized partial sum and the limiting Gaussian
distribution for stationary martingale difference sequences or stationary
sequences satisfying projective criteria. Applications to functions of linear
processes and to functions of expanding maps of the interval are given.
| arxiv topic:math.ST math.PR stat.TH |
arxiv_dataset-382712.0279 | Heisenberg modules over real multiplication noncommutative tori and
related algebraic structures
math.QA
We review some aspects of the theory of noncommutative two-tori with real
multiplication focusing on the role played by Heisenberg groups in the
definition of algebraic structures associated to these noncommutative spaces.
| arxiv topic:math.QA |
arxiv_dataset-383712.0379 | The N=1 triplet vertex operator superalgebras
math.QA hep-th math-ph math.MP math.RT
We introduce a new family of C_2-cofinite N=1 vertex operator superalgebras
SW(m), $m \geq 1$, which are natural super analogs of the triplet vertex
algebra family W(p), $p \geq 2$, important in logarithmic conformal field
theory. We classify irreducible SW(m)-modules and discuss logarithmic modules.
We also compute bosonic and fermionic formulas of irreducible SW(m) characters.
Finally, we contemplate possible connections between the category of
SW(m)-modules and the category of modules for the quantum group
U^{small}_q(sl_2), q=e^{\frac{2 \pi i}{2m+1}}, by focusing primarily on
properties of characters and the Zhu's algebra A(SW(m)). This paper is a
continuation of arXiv:0707.1857.
| arxiv topic:math.QA hep-th math-ph math.MP math.RT |
arxiv_dataset-384712.0479 | First quintuplet frequency solution of a Blazhko variable: light curve
analysis of RV UMa
astro-ph
RV UMa is one of the RRab stars showing regular large amplitude light curve
modulation. Extended photoelectric observations of RV UMa obtained at the
Konkoly Observatory were published by Kanyo (1976). The analysis of the data
was published by Kovacs (1995). After detecting an error in the reduction
procedure of the published Konkoly data, corrected photometric data are
presented with additional, previously unpublished measurements.
The reanalysis of the combination of the corrected Konkoly data supplemented
with Preston & Spinrad's (1967) observations has led to the discovery that the
adequate mathematical model of the light curve is, in fact, a quintuplet,
instead of a triplet frequency solution. This finding has crucial importance in
the interpretation of the Blazhko phenomenon, as triplet (doublet) is the
preferred structure in the resonance models, quintuplet in the magnetic models.
Period changes of both the pulsation and the modulation light variations of
RV UMa have been detected based on its century long photometric observations.
An overall anticorrelation between the pulsation and the modulation period
changes can be defined with dP_{Bl} / dP_0 = -8.6 pm 10^4 gradient, i.e., the
modulation period is longer if the pulsation period is shorter. Between 1946
and 1975 the pulsation and modulation periods showed, however, parallel
changes, which points to that there is no strict relation between the changes
in the periods of the pulsation and the modulation.
| arxiv topic:astro-ph |
arxiv_dataset-385712.0579 | Kinematics of a hot massive accretion disk candidate
astro-ph
Characterizing rotation, infall and accretion disks around high-mass
protostars is an important topic in massive star formation research. With the
Australia Telescope Compact Array and the Very Large Array we studied a massive
disk candidate at high angular resolution in ammonia (NH3(4,4) & (5,5)) tracing
the warm disk but not the envelope. The observations resolved at ~0.4''
resolution (corresponding to ~1400AU) a velocity gradient indicative of
rotation perpendicular to the molecular outflow. Assuming a Keplerian accretion
disk, the estimated protostar-disk mass would be high, similar to the
protostellar mass. Furthermore, the position-velocity diagram exhibits
additional deviation from a Keplerian rotation profile which may be caused by
infalling gas and/or a self-gravitating disk. Moreover, a large fraction of the
rotating gas is at temperatures >100K, markedly different to typical low-mass
accretion disks. In addition, we resolve a central double-lobe cm continuum
structure perpendicular to the rotation. We identify this with an ionized,
optically thick jet.
| arxiv topic:astro-ph |
arxiv_dataset-386712.0679 | Asymptotic normality of the Quasi Maximum Likelihood Estimator for
multidimensional causal processes
math.ST stat.TH
Strong consistency and asymptotic normality of the Quasi-Maximum Likelihood
Estimator (QMLE) are given for a general class of multidimensional causal
processes. For particular cases already studied in the literature (for instance
univariate or multivariate GARCH, ARCH, ARMA-GARCH processes) the assumptions
required for establishing these results are often weaker than existing
conditions. The QMLE asymptotic behavior is also given for numerous new
examples of univariate or multivariate processes (for instance TARCH or NLARCH
processes).
| arxiv topic:math.ST stat.TH |
arxiv_dataset-387712.0779 | Frequency-dependent fluctuation-dissipation relations in granular gases
cond-mat.soft cond-mat.stat-mech
The Green-Kubo relation for two models of granular gases is discussed. In the
Maxwell model in any dimension, the effective temperature obtained from the
Green-Kubo relation is shown to be frequency independent, and equal to the
average kinetic energy, known as the granular temperature. In the second model
analyzed, a mean-field granular gas, the collision rate of a particle is taken
to be proportional to its velocity. The Green-Kubo relation in the high
frequency limit is calculated for this model, and the effective temperature in
this limit is shown to be equal to the granular temperature. This result, taken
together with previous results, showing a difference between the effective
temperature at zero frequency (the Einstein relation) and the granular
temperature, shows that the Green-Kubo relation for granular gases is violated.
| arxiv topic:cond-mat.soft cond-mat.stat-mech |
arxiv_dataset-388712.0879 | Quasi-particle propagation in quantum Hall systems
cond-mat.mes-hall
We study various geometrical aspects of the propagation of particles obeying
fractional statistics in the physical setting of the quantum Hall system. We
find a discrete set of zeros for the two-particle kernel in the lowest Landau
level; these arise from a combination of a two-particle Aharonov-Bohm effect
and the exchange phase related to fractional statistics. The kernel also shows
short distance exclusion statistics, for instance, in a power law behavior as a
function of initial and final positions of the particles. We employ the
one-particle kernel to compute impurity-mediated tunneling amplitudes between
different edges of a finite-sized quantum Hall system and and find that they
vanishes for certain strengths and locations of the impurity scattering
potentials. We show that even in the absence of scattering, the correlation
functions between different edges exhibits unusual features for a narrow enough
Hall bar.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-389712.0979 | Equivalence of conditional and external field ensembles in absorbing
state phase transitions
cond-mat.stat-mech
I comment on the relation between two sampling methods for absorbing state
models. It is shown that a certain ensemble without external field conditional
to activity coincides with the unconditional ensemble for sufficiently small
external field. The actual physical processes involved are identical and the
derivation of the identity of the scaling behaviour relies on a single
(established) scaling law. While the conditional ensemble by construction does
not contain information about the system with large external field, it contains
all information about the limit of vanishing external field and about the
vicinity of the critical point: Finite size scaling as well as critical scaling
in the temperature-like variable or in (small) external field.
| arxiv topic:cond-mat.stat-mech |
arxiv_dataset-390712.1079 | Orbit closures in the enhanced nilpotent cone
math.RT math.CO
We study the orbits of $G=\mathrm{GL}(V)$ in the enhanced nilpotent cone
$V\times\mathcal{N}$, where $\mathcal{N}$ is the variety of nilpotent
endomorphisms of $V$. These orbits are parametrized by bipartitions of $n=\dim
V$, and we prove that the closure ordering corresponds to a natural partial
order on bipartitions. Moreover, we prove that the local intersection
cohomology of the orbit closures is given by certain bipartition analogues of
Kostka polynomials, defined by Shoji. Finally, we make a connection with Kato's
exotic nilpotent cone in type C, proving that the closure ordering is the same,
and conjecturing that the intersection cohomology is the same but with degrees
doubled.
| arxiv topic:math.RT math.CO |
arxiv_dataset-391712.1179 | Life on the fast lane: the burst mode at the VLT at present and in the
future
astro-ph
The recent implementation of the high-speed burst mode at the ISAAC
instrument on UT1, and its propagation to other ESO instruments, has opened the
door to observational capabilities which hold the potential for a wealth of
novel results. In the ELT era, when the accent will likely be on lengthy
programs aimed at the best sensitivity and angular resolution, the VLT
telescopes could continue to play a significant and largely unique role by
performing routinely observations of transient events at high temporal
resolution. In our contribution, we provide details on two such kinds of
observations, namely lunar occultations of stars and of asteroids. For the
first ones, we report on two passages of the Moon in regions with high stellar
density as the Galactic Center. The VLT-UT1 telescope was used for the first
time to record successfully 53 and 71 occultations on March 22 and August 6,
2006, with an angular resolution of 0.5-1 milliarcsecond and $K\sim12.5$
limiting magnitude. We note that the angular resolution is superior to that
achieved at present by Adaptive Optics on any telescope, and also superior to
that foreseen for the ELT at the same wavelength. LO are also very efficient in
terms of telescope time. We present some of the results, including the
discovery of close binaries, and the detection and study of compact
circumstellar components of cool giants, AGB stars and embedded IR sources.
Rest of the abstract follows at the paper
| arxiv topic:astro-ph |
arxiv_dataset-392712.1279 | Kleene, Rogers and Rice Theorems Revisited in C and in Bash
cs.LO
The recursion theorem in the weak form {e}(z)=x(e,z) (universal function not
needed) and in Rogers form {n}(z)={{x}(n)}(z) and Rice theorem are proved a
first time using programs in C, and a second time with scripts in Bash.
| arxiv topic:cs.LO |
arxiv_dataset-393712.1379 | Three Dimensional Molecular Line Transfer Study of Extragalactic ISM :
AGN/Starburst Connection
astro-ph
Molecular gas in external galaxies is a subject of crucial importance for
observational and theoretical studies of galaxy formation. Compact molecular
gas around an active galactic nuclei (AGN) is expected to be an energy budget
of AGN and/or nuclear starburst. Recent observational studies suggest that line
ratios in millimeter and submillimeter band may be a good tool to reveal the
long-standing question on the origin of activity -- AGN or nuclear starburst.
We have constructed a powerful "telescope" of theory, three-dimensional nonLTE
line transfer code, preceding the high resolution and sensitivity observations
such as ALMA.
| arxiv topic:astro-ph |
arxiv_dataset-394712.1479 | P Wave Baryons in Field Correlator Method: Hyperons
hep-ph
We provide an investigation of the P-wave hyperons employing the field
correlator method in QCD. This method allows to derive the Effective
Hamiltonian successfully applied to the meson and ground state baryon spectra.
The hyperon spectrum appears to be expressed through two parameters relevant to
QCD, the string tension \sigma, the strong coupling constant \alpha_s, and the
bare strange quark mass m_s. Using these parameters a unified description of
the ground and excited hyperon states is achieved. We also briefly consider the
nucleon P-wave excitations. In particular, we predict that both the nucleon and
hyperon states have the similar cost (in \Delta L) ~460 MeV.
| arxiv topic:hep-ph |
arxiv_dataset-395712.1579 | Astrophysical Limits on Lorentz Violation for Pions
hep-ph
Pions, like nucleons, are composed primarily of up and down quarks and
gluons. Constraints on spin-independent Lorentz violation in the proton,
neutron, and pion sectors translate into bounds on Lorentz violation for the
fundamental fields. The best bounds on pion Lorentz violation come from
astrophysical measurements. The absence of the absorption process gamma -->
pi^(+) + pi^(-) for up to 50 TeV photons constrains the possibility that pions'
maximum achievable velocities are less than 1 at the 1.5 x 10^(-11) level. The
fact that pions with energies up to 30 TeV are observed to decay into photons
rather than hadrons bounds the possibility of a maximum velocity greater than 1
at the $2 x 10^(-9) level. This provides the first two-sided bounds on Lorentz
violation for pions.
| arxiv topic:hep-ph |
arxiv_dataset-396712.1679 | Semiclassical Analysis for Hartree equation
math.AP math-ph math.MP
We justify WKB analysis for Hartree equation in space dimension at least
three, in a regime which is supercritical as far as semiclassical analysis is
concerned. The main technical remark is that the nonlinear Hartree term can be
considered as a semilinear perturbation. This is in contrast with the case of
the nonlinear Schrodinger equation with a local nonlinearity, where quasilinear
analysis is needed to treat the nonlinearity.
| arxiv topic:math.AP math-ph math.MP |
arxiv_dataset-397712.1779 | Neutrino oscillations in a stochastic model for space-time foam
hep-ph astro-ph hep-th
We study decoherence models for flavour oscillations in four-dimensional
stochastically fluctuating space times and discuss briefly the sensitivity of
current neutrino experiments to such models. We pay emphasis on demonstrating
the model dependence of the associated decoherence-induced damping coefficients
in front of the oscillatory terms in the respective transition probabilities
between flavours. Within the context of specific models of foam, involving
point-like D-branes and leading to decoherence-induced damping which is
inversely proportional to the neutrino energies, we also argue that future
limits on the relevant decoherence parameters coming from TeV astrophysical
neutrinos, to be observed in ICE-CUBE, are not far from theoretically expected
values with Planck mass suppression. Ultra high energy neutrinos from Gamma Ray
Bursts at cosmological distances can also exhibit in principle sensitivity to
such effects.
| arxiv topic:hep-ph astro-ph hep-th |
arxiv_dataset-398712.1879 | Ultrafast Electron-Phonon Decoupling in Graphite
cond-mat.other cond-mat.mtrl-sci
We report the ultrafast dynamics of the 47.4 THz coherent phonons of graphite
interacting with a photoinduced non-equilibrium electron-hole plasma. Unlike
conventional materials, upon photoexcitation the phonon frequency of graphite
upshifts, and within a few picoseconds relaxes to the stationary value. Our
first-principles density functional calculations demonstrate that the phonon
stiffening stems from the light-induced decoupling of the non-adiabatic
electron-phonon interaction by creating the non-equilibrium electron-hole
plasma. Time-resolved vibrational spectroscopy provides a window on the
ultrafast non-equilibrium electron dynamics.
| arxiv topic:cond-mat.other cond-mat.mtrl-sci |
arxiv_dataset-399712.1979 | Quantum Error Correcting Codes Using Qudit Graph States
quant-ph
Graph states are generalized from qubits to collections of $n$ qudits of
arbitrary dimension $D$, and simple graphical methods are used to construct
both additive and nonadditive quantum error correcting codes. Codes of distance
2 saturating the quantum Singleton bound for arbitrarily large $n$ and $D$ are
constructed using simple graphs, except when $n$ is odd and $D$ is even.
Computer searches have produced a number of codes with distances 3 and 4, some
previously known and some new. The concept of a stabilizer is extended to
general $D$, and shown to provide a dual representation of an additive graph
code.
| arxiv topic:quant-ph |
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