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arxiv_dataset-23001012.0632 | Generalizations of Quantum Discord
quant-ph
The original definition of quantum discord of bipartite states was defined
over projective measurements, in this paper we discuss some generalizations of
it. These generalizations are defined over general measurements, rank-one
general measurements or Neumark extension measurements. We investigate the
nonnegativity, zero-discord sets of all these quantum discords and some
properties about them.
| arxiv topic:quant-ph |
arxiv_dataset-23011012.0732 | Magnetic vortex lattice in HgBa2CuO4+x observed by small-angle neutron
scattering
cond-mat.supr-con
We report a direct observation of the magnetic vortex lattice in the model
high-temperature superconductor HgBa2CuO4+x. Using small-angle neutron
scattering on high-quality crystals, we observe two equal domains of
undistorted triangular vortex lattices well-aligned with the tetragonal
crystallographic axes. The signal decreases rapidly with increasing magnetic
field and vanishes above 0.4 Tesla, which we attribute to a crossover from a
three-dimensional to a two-dimensional vortex system, similar to previous
results for the more anisotropic compound Bi2.15Sr1.95CaCu2O8+x. Our result
indicates that a triangular vortex lattice at low magnetic fields is a generic
property to cuprates with critical temperatures above 80 K.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-23021012.0832 | Shell structure and orbit bifurcations in finite fermion systems
nucl-th math-ph math.MP
We first give an overview of the shell-correction method which was developed
by V. M. Strutinsky as a practicable and efficient approximation to the general
selfconsistent theory of finite fermion systems suggested by A. B. Migdal and
collaborators. Then we present in more detail a semiclassical theory of shell
effects, also developed by Strutinsky following original ideas of M.
Gutzwiller. We emphasize, in particular, the influence of orbit bifurcations on
shell structure. We first give a short overview of semiclassical trace
formulae, which connect the shell oscillations of a quantum system with a sum
over periodic orbits of the corresponding classical system, in what is usually
called the "periodic orbit theory". We then present a case study in which the
gross features of a typical double-humped nuclear fission barrier, including
the effects of mass asymmetry, can be obtained in terms of the shortest
periodic orbits of a cavity model with realistic deformations relevant for
nuclear fission. Next we investigate shell structures in a spheroidal cavity
model which is integrable and allows for far-going analytical computation. We
show, in particular, how period-doubling bifurcations are closely connected to
the existence of the so-called "superdeformed" energy minimum which corresponds
to the fission isomer of actinide nuclei. Finally, we present a general class
of radial power-law potentials which approximate well the shape of a
Woods-Saxon potential in the bound region, give analytical trace formulae for
it and discuss various limits (including the harmonic oscillator and the
spherical box potentials).
| arxiv topic:nucl-th math-ph math.MP |
arxiv_dataset-23031012.0932 | Random-matrix theory of Andreev reflection from a topological
superconductor
cond-mat.mes-hall
We calculate the probability distribution of the Andreev reflection
eigenvalues R_n at the Fermi level in the circular ensemble of random-matrix
theory. Without spin-rotation symmetry, the statistics of the electrical
conductance G depends on the topological quantum number Q of the
superconductor. We show that this dependence is nonperturbative in the number N
of scattering channels, by proving that the p-th cumulant of G is independent
of Q for p<N/d (with d=2 or d=1 in the presence or in the absence of
time-reversal symmetry). A large-N effect such as weak localization cannot,
therefore, probe the topological quantum number. For small N we calculate the
full distribution P(G) of the conductance and find qualitative differences in
the topologically trivial and nontrivial phases.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-23041012.1032 | A faithful linear-categorical action of the mapping class group of a
surface with boundary
math.GT math.QA
We show that the action of the mapping class group on bordered Floer homology
in the second to extremal spin^c-structure is faithful. This paper is designed
partly as an introduction to the subject, and much of it should be readable
without a background in Floer homology.
| arxiv topic:math.GT math.QA |
arxiv_dataset-23051012.1132 | New perturbation expansions in quantum chromodynamics and the
determination of $\alpha_s$
hep-ph
We consider a new class of perturbation expansions, which incorporate in a
systematic way the available information about the divergent character of the
perturbation series in QCD. The new expansion functions, which replace the
powers of the coupling, are defined by the analytic continuation in the Borel
plane, achieved through an optimal conformal mapping. We consider several
possibilities of implementing the known behaviour of the Borel transform near
the leading singularities in the complex plane and using the corresponding
expansions. These expansions have the same asymptotic convergence rate, but
differ at low orders. We show that the new expansions allow a precise
determination of the strong coupling $\alpha_s$ from the hadronic decays of the
$\tau$ lepton.
| arxiv topic:hep-ph |
arxiv_dataset-23061012.1232 | Nucleon form factors: the space-time connection
hep-ph
Analyticity of nucleon form factors allows to derive sum rules which, using
space-like and time-like data as input, can give unique information about
behaviors in energy regions not experimentally accessible. Taking advantage
from new time-like data on proton-antiproton differential cross section and
hence the possibility to separate electric and magnetic form factors also in
the time-like region, we verify the consistency of the asymptotic behavior
predicted by the perturbative QCD for the proton magnetic form factor.
| arxiv topic:hep-ph |
arxiv_dataset-23071012.1332 | Time-Symmetric Cellular Automata
cs.DM cs.FL nlin.CG
Together with the concept of reversibility, another relevant physical notion
is time-symmetry, which expresses that there is no way of distinguishing
between backward and forward time directions. This notion, found in physical
theories, has been neglected in the area of discrete dynamical systems. Here we
formalize it in the context of cellular automata and establish some basic facts
and relations. We also state some open problems that may encourage further
research on the topic.
| arxiv topic:cs.DM cs.FL nlin.CG |
arxiv_dataset-23081012.1432 | Homogeneous coexistence of SDW and SC states in CaFe(1-x)Co(x)AsF
studied by nuclear magnetic resonance
cond-mat.supr-con
We investigated the homogeneous coexistence of spin-density-wave (SDW) and
superconducting (SC) states via 75As-nuclear magnetic resonance (NMR) in
CaFe(1-x)Co(x)AsF and found that the electronic and magnetic properties of this
compound are intermediate between those of LaFeAsO(1-x)F(x) and
Ba(Fe(1-x)Co(x))2As2. For 6% Co-doped samples, the paramagnetic spectral weight
completely disappears in the crossover regime between the SDW and SC phases
followed by the anomalous behavior of relaxation rate (1/T1), implying that the
two phases are not segregated. The 59Co-NMR spectra show that spin moments are
not commensurate but spatially modulated. These experimental results suggest
that incommensurate SDW (IC-SDW) and SC states are compatible in this compound.
| arxiv topic:cond-mat.supr-con |
arxiv_dataset-23091012.1532 | Rational subsets of groups
cs.FL cs.DM math.GR
This text, Chapter 23 in the "AutoMathA" handbook, is devoted to the study of
rational subsets of groups, with particular emphasis on the automata-theoretic
approach to finitely generated subgroups of free groups. Indeed, Stallings'
construction, associating a finite inverse automaton with every such subgroup,
inaugurated a complete rewriting of free group algorithmics, with connections
to other fields such as topology or dynamics.
Another important vector in the chapter is the fundamental Benois' Theorem,
characterizing rational subsets of free groups. The theorem and its
consequences really explain why language theory can be successfully applied to
the study of free groups. Rational subsets of (free) groups can play a major
role in proving statements (a priori unrelated to the notion of rationality) by
induction. The chapter also includes related results for more general classes
of groups, such as virtually free groups or graph groups.
| arxiv topic:cs.FL cs.DM math.GR |
arxiv_dataset-23101012.1632 | Benchmarking triple stores with biological data
cs.DB
We have compared the performance of five non-commercial triple stores,
Virtuoso-open source, Jena SDB, Jena TDB, SWIFT-OWLIM and 4Store. We examined
three performance aspects: the query execution time, scalability and run-to-run
reproducibility. The queries we chose addressed different ontological or
biological topics, and we obtained evidence that individual store performance
was quite query specific. We identified three groups of queries displaying
similar behavior across the different stores: 1) relatively short response
time, 2) moderate response time and 3) relatively long response time. OWLIM
proved to be a winner in the first group, 4Store in the second and Virtuoso in
the third. Our benchmarking showed Virtuoso to be a very balanced performer -
its response time was better than average for all the 24 queries; it showed a
very good scalability and a reasonable run-to-run reproducibility.
| arxiv topic:cs.DB |
arxiv_dataset-23111012.1732 | Optically erasing disorder in semiconductor microcavities with dynamic
nuclear polarization
cond-mat.mes-hall
The mean squared value of the photonic disorder is found to be reduced by a
factor of 100 in a typical GaAs based microcavity, when exposed to a circularly
polarized continuous wave optical pump without any special spatial patterning.
Resonant excitation of the cavity mode excites a spatially non-uniform
distribution of spin-polarized electrons, which depends on the photonic
disorder profile. Electrons transfer spin to nuclei via the hyperfine contact
interaction, inducing a long-living Overhauser magnetic field able to modify
the potential of exciton-polaritons.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-23121012.1832 | Infrared chiral anomaly at finite temperature
hep-th hep-ph
We study the Schwinger model at finite temperature and show that a
temperature dependent chiral anomaly may arise from the long distance behavior
of the electric field. At high temperature this anomaly depends linearly on the
temperature $T$ and is present not only in the two point function, but also in
all even point amplitudes.
| arxiv topic:hep-th hep-ph |
arxiv_dataset-23131012.1932 | Effect of splitting of the neutron and proton effective mass on nuclear
symmetry energy at finite temperature
nucl-th
We present the temperature and density dependence of symmetry energy for
nuclear matter at finite temperature based on the approach of the
thermodynamics with Skyrme energy density functional. We first classify the
Skyrme interactions into 7 groups according to the range of neutron and proton
effective mass in neutron matter limit(99.99 per cent neutron in the matter).
We find that there is obvious correlation between the temperature dependence of
the symmetry energy and the splitting of the neutron and proton effective mass.
For some Skyrme interactions with $m^{*}_{n}>m^{*}_{p}$ and strong splitting of
the neutron and proton effective mass in asymmetric nuclear matter, a
transition of the temperature dependence of symmetry energy from decreasing
with temperature at low densities to increasing with temperature at high
densities appears. For other Skyrme interactions, we do not observe such
phenomenon. Our study show that the symmetry energy in hot asymmetric matter
not only depends on symmetry potential part but also on the splitting of the
neutron and proton effective mass to a certain extent.
| arxiv topic:nucl-th |
arxiv_dataset-23141012.2032 | Modeling neutrino-nucleus interactions. Do we need a new paradigm?
nucl-th
The availability of the double-differential charged-current neutrino cross
section, measured by the MiniBooNE collaboration using a carbon target, allows
for a systematic comparison of nuclear effects in quasi-elastic electron and
neutrino scattering. The results of theoretical studies based on the impulse
approximation scheme and state-of-the-art models of the nuclear spectral
functions suggest that the electron cross section and the flux averaged
neutrino cross sections corresponding to the same target and seemingly
comparable kinematical conditions can not be described within the same
theoretical scheme using the value ofthe nucleon axial mass obtained from
deuterium measurements. I analyze the assumptions underlying the treatment of
electron scattering data, and argue that the development of a new {\em
paradigm}, suitable for application to processes in which the lepton kinematics
is not fully determined, will be required.
| arxiv topic:nucl-th |
arxiv_dataset-23151012.2132 | Second-order polaron resonances in self assembled quantum dots
cond-mat.mes-hall
We theoretically study the optical properties of an InAs/GaAs quantum dot
(QD) near the area of the second-order resonance between an electron confined
in the QD and two longitudinal optical phonons. We present the absorption
spectra of an inhomogeneously broadened QD ensemble and show that the minimal
model needed for an accurate description of such a system needs to account for
3-phonon states. We study also the influence of the QD height to width ratio on
the optical properties of the polaron system. The dependence of the width of
the resonance and the position of the second-order resonant feature on the
height to width ratio is presented.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-23161012.2232 | Slepton Mass Matrices, mu -> e gamma Decay and EDM in SUSY S4 Flavor
Model
hep-ph
We discuss slepton mass matrices in the $S_4$ flavor model with SUSY SU(5)
GUT. By considering the gravity mediation within the framework of supergravity
theory, we estimate the SUSY breaking terms in the slepton mass matrices, which
contribute to the $\mu \rightarrow e + \gamma$ decay.
We obtain a lower bound for the ratio of $\mu\rightarrow e\gamma$ as
$10^{-13}$ if $m_{\text{SUSY}}$ and $m_{1/2}$ are below 500GeV. The off
diagonal terms of slepton mass matrices also contribute to EDM of leptons. The
predicted electron EDM is around $10^{-29}-10^{-28}$cm. Our predictions are
expected to be tested in the near future experiment.
| arxiv topic:hep-ph |
arxiv_dataset-23171012.2332 | On the Shapley-like Payoff Mechanisms in Peer-Assisted Services with
Multiple Content Providers
cs.GT cs.NI
This paper studies an incentive structure for cooperation and its stability
in peer-assisted services when there exist multiple content providers, using a
coalition game theoretic approach. We first consider a generalized coalition
structure consisting of multiple providers with many assisting peers, where
peers assist providers to reduce the operational cost in content distribution.
To distribute the profit from cost reduction to players (i.e., providers and
peers), we then establish a generalized formula for individual payoffs when a
"Shapley-like" payoff mechanism is adopted. We show that the grand coalition is
unstable, even when the operational cost functions are concave, which is in
sharp contrast to the recently studied case of a single provider where the
grand coalition is stable. We also show that irrespective of stability of the
grand coalition, there always exist coalition structures which are not
convergent to the grand coalition. Our results give us an important insight
that a provider does not tend to cooperate with other providers in
peer-assisted services, and be separated from them. To further study the case
of the separated providers, three examples are presented; (i) underpaid peers,
(ii) service monopoly, and (iii) oscillatory coalition structure. Our study
opens many new questions such as realistic and efficient incentive structures
and the tradeoffs between fairness and individual providers' competition in
peer-assisted services.
| arxiv topic:cs.GT cs.NI |
arxiv_dataset-23181012.2432 | The three-dimensional gauge-glass model
cond-mat.dis-nn cond-mat.stat-mech
We investigate the temperature-disorder (T-S) phase diagram of a
three-dimensional gauge glass model, which is a cubic-lattice nearest-neighbor
XY model with quenched random phase shifts A_xy at the bonds, by numerical
Monte Carlo simulations. We consider the uncorrelated phase-shift distribution
P(A_xy)\sim \exp[(cos A_xy)/S], which has the pure XY model and the uniform
distribution of random shifts as extreme cases at S=0 and S->infty
respectively, and which gives rise to equal magnetic and overlap correlation
functions when T=S. While the high-temperature phase is always paramagnetic, at
low temperatures there is a ferromagnetic phase for weak disorder (small S) and
a glassy phase at large disorder (large S). These three phases are separated by
transition lines with different magnetic and glassy critical behaviors. The
disorder induced by the random shifts turns out to be irrelevant at the
paramagnetic-ferromagnetic transition line, where the critical behavior belongs
to the 3D XY universality class of pure systems; disorder gives only rise to
very slowly decaying scaling corrections. The glassy critical behavior along
the finite-temperature paramagnetic-glassy transition line belongs to the
gauge-glass universality class, with a quite large critical exponent nu=3.2(4).
These transition lines meet at a multicritical point M, located at
T=S=0.7840(2). The low-temperature ferromagnetic and glassy phases are
separated by a third transition line, from M down to the T=0 axis, which is
slightly reentrant.
| arxiv topic:cond-mat.dis-nn cond-mat.stat-mech |
arxiv_dataset-23191012.2532 | Research Note on a Parabolic Heat-Balance Integral Method with
Unspecified Exponent: An Entropy Generation Approach in Optimal Profile
Determination
math-ph math.MP
The heat-balance integral method of Goodman is studied with two simple 1-D
heat conduction problems with prescribed temperature and flux boundary
conditions. These classical problems with well known exact solutions enable to
demonstrate the heat-balance integral method performance by a parabolic profile
and the entropy generation minimization concept in definition of the
appropriate profile exponent. The basic assumption generating the additional
constraints needed to perform the solution is based on the requirement to
minimize the difference in the local thermal entropy generation rates
calculated by the approximate and the exact profile, respectively. This concept
is easily applicable since the general concept has simple implementation of the
condition requiring the thermal entropy generations calculated through both
profiles to be the same at the boundary. The entropy minimization generation
approach automatically generates the additional requirement which is deficient
in the set of conditions defined by the heat-balance integral method concept.
| arxiv topic:math-ph math.MP |
arxiv_dataset-23201012.2632 | There are only finitely many distance-regular graphs with valency k at
least three, fixed ratio k2/k and large diameter
math.CO
In this paper, we show that for given positive integer C, there are only
finitely many distance-regular graphs with valency k at least three, diameter D
at least six and k2/k<=C. This extends a conjecture of Bannai and Ito.
| arxiv topic:math.CO |
arxiv_dataset-23211012.2732 | Estimating f_NL and g_NL from Massive High-Redshift Galaxy Clusters
astro-ph.CO
There are observations of 15 high-redshift massive galaxy clusters, which
have an extremely small probability with a purely Gaussian initial curvature
perturbation. Here we revisit the estimation of the contribution of
non-Gaussianities to the cluster mass function and point out serious problems
that have resulted in the application of the mass function out of the range of
its validity. We remedy the situation and show that the values of f_NL
previously claimed to completely reconcile (i.e. at ~100% confidence) the
existence of the clusters with LambdaCDM are unphysically small. However, for
WMAP cosmology and at 95% confidence, we arrive at the limit f_NL>411, which is
similar to previous estimates. We also explore the possibility of a large g_NL
as the reason for the observed excess of the massive galaxy clusters. This
scenario, g_NL>2*10^6, appears to be in more agreement with CMB and LSS limits
for the non-Gaussianity parameters and could also provide an explanation for
the overabundance of large voids in the early universe.
| arxiv topic:astro-ph.CO |
arxiv_dataset-23221012.2832 | A Longitudinal Study of Non-Voice Mobile Phone Usage by Teens from an
Underserved Urban Community
cs.HC cs.CY
We report a user study of over four months on the non-voice usage of mobile
phones by teens from an underserved urban community in the USA where a
community-wide, open-access Wi-Fi network exists. We instrumented the phones to
record quantitative information regarding their usage and location in a
privacy-respecting manner. We conducted focus group meetings and interviewed
participants regularly for qualitative data. We present our findings on what
applications our participants used and how their usage changed over time. The
findings highlight the challenges to evaluating the usability of mobile systems
and the value of long-term methodologies. Based on our findings, we analyze the
unique values of mobile phones, as a platform technology. Our study shows that
the usage is highly mobile, location-dependent, and serves multiple social
purposes for the participants. Furthermore, we present concrete findings on how
to perform and analyze similar user studies on mobile phones, including four
contributing factors to usage evolution, and provide guidelines for their
design and evaluation.
| arxiv topic:cs.HC cs.CY |
arxiv_dataset-23231012.2932 | The Magnetic Field of the Milky Way Galaxy
astro-ph.GA
Cosmic magnetic fields are an integral component of the interstellar medium
(ISM), having influence on scales ranging from star formation to galactic
dynamics. While observations of external galaxies offer a `birds-eye-view' of
magnetic fields within galaxies, it is equally important to explore the
magnetic field of our own Milky Way Galaxy, which offers a more detailed,
albeit more complicated view. Over the past decade there has been a significant
increase in interest in the Galactic magnetic field, fueled largely by
innovations developed through the Canadian Galactic Plane Survey. In this
paper, I review the current state of understanding of the Galactic magnetic
field, and discuss briefly new and future observations that will provide
exciting new insights about the field.
| arxiv topic:astro-ph.GA |
arxiv_dataset-23241012.3032 | Is the present cosmic expansion decelerating?
astro-ph.CO
We probe the recent cosmic expansion by directly reconstructing the
deceleration parameter $q(z)$ at recent times with a linear expansion at $z=0$
using the low redshift SNIa and BAO data. Our results show that the
observations seem to favor a slowing down of the present cosmic acceleration.
Using only very low redshift SNIa data, for example, those within $z<0.1$ or
$0.2$, we find that our Universe may have already entered a decelerating
expansion era since a positive $q(0)$ seems to be favored. This result is
further supported by a different approach which aims to reconstruct $q(z)$ in
the whole redshift region. So, the accelerating cosmic expansion may be just a
transient phenomenon.
| arxiv topic:astro-ph.CO |
arxiv_dataset-23251012.3132 | Pointwise characteristic factors for the multiterm return times theorem
math.DS
This paper is an update and extension of a result the authors first proved in
2003. The goal of this paper is to study factors which are known to be
L^2-characteristic for certain nonconventional averages and prove that these
factors are pointwise characteristic for the multidimensional return times
averages.
| arxiv topic:math.DS |
arxiv_dataset-23261012.3232 | Internal structure of resonant Lambda(1405) state in chiral dynamics
nucl-th
The internal structure of the resonant Lambda(1405) state is investigated
based on meson-baryon coupled-channels chiral dynamics, by evaluating density
distributions obtained from the form factors of the Lambda(1405) state. The
form factors are defined as an extension of the ordinary stable particles and
are directly evaluated from the meson-baryon scattering amplitude, paying
attention to the charge conservation of the probe interaction. For the resonant
Lambda(1405) state we calculate the density distributions in two ways. One is
on the pole position of the Lambda(1405) in the complex energy plane, which
evaluates the resonant Lambda(1405) structure without contamination from
nonresonant backgrounds, and another on the real energy axis around the
Lambda(1405) resonance energy, which may be achieved in experiments. Using
sereval probe interactions and channel decomposition, we separate the various
contributions to the internal structure of the Lambda(1405). As a result, we
find that the resonant Lambda(1405) state is composed of widely spread Kbar
around N, which gives dominant component inside the Lambda(1405), with escaping
pi Sigma component. Furthermore, we consider Kbar N bound state without decay
channels, with which we can observe the internal structure of the bound state
within real numbers. We also study the dependence of the form factors on the
binding energy and meson mass. This verifies that the form factor defined
through the scattering amplitude serves as a natural generalization of the form
factor for the resonance state. The relation between the interaction strength
and the meson mass shows that the physical kaon mass appears to be within the
suitable range to form a molecular bound state with the nucleon through the
chiral SU(3) interaction.
| arxiv topic:nucl-th |
arxiv_dataset-23271012.3332 | Virtual Compton Scattering off a Spinless Target in the AdS/QCD
correspondence
hep-ph hep-th
We perform a study of the doubly virtual Compton scattering off a spinless
target gamma* P -> gamma* P' within the Anti-de Sitter(AdS)/QCD formalism. We
find that the general structure allowed by the Lorentz invariance and gauge
invariance of the Compton amplitude is not easily reproduced with the standard
recipes of the AdS/QCD correspondence. In the soft-photon regime, where the
semi-classical approximation is supposed to apply best, we show that the
measurements of the electric and magnetic polarizabilities of a target like the
charged pion in real Compton scattering, can already serve as stringent tests,
and presumably exclude results based on the AdS/QCD correspondence in its
minimal version.
| arxiv topic:hep-ph hep-th |
arxiv_dataset-23281012.3432 | On invariant Gibbs measures conditioned on mass and momentum
math.PR math.AP
We construct a Gibbs measure for the nonlinear Schrodinger equation (NLS) on
the circle, conditioned on prescribed mass and momentum: d \mu_{a,b} = Z^{-1}
1_{\int_T |u|^2 = a} 1_{i \int_T u \bar{u}_x = b} exp (\pm1/p \int_T |u|^p -
1/2 \int_{\T} |u|^2) d P for a \in R^+ and b \in R, where P is the
complex-valued Wiener measure on the circle. We also show that \mu_{a,b} is
invariant under the flow of NLS. We note that i \int_\T u \bar{u}_x is the Levy
stochastic area, and in particular that this is invariant under the flow of
NLS.
| arxiv topic:math.PR math.AP |
arxiv_dataset-23291012.3532 | Group theoretic formulation of complementarity
quant-ph
We generalize Bohr's complementarity principle for wave and particle
properties to arbitrary quantum systems. We begin by noting that a
particle-like state is represented by a spatially-localized wave function and
its narrow probability density is displaced by spatial translations. In
contrast a wave-like state is represented by a spatially-delocalized wave
function and the corresponding broad position probability density is invariant
to spatial translations. The wave-particle dichotomy can therefore be seen as a
competition between displacement and invariance of the state with respect to
spatial translations. We generalize this dichotomy to arbitrary quantum systems
with finite dimensional Hilbert spaces as follows. We use arbitrary finite
symmetry groups to represent transformations of the quantum system. The
symmetry (i.e. invariance) or asymmetry (i.e. displacement) of a given state
with respect to transformations of the group are identified with the
generalized wave and particle nature, respectively. We adopt a measure of wave
and particle properties based on the amount of information that can be encoded
in the symmetric and asymmetric parts of the state.
| arxiv topic:quant-ph |
arxiv_dataset-23301012.3632 | Langevin theory of fluctuations in the discrete Boltzmann equation
physics.comp-ph cond-mat.soft physics.flu-dyn
The discrete Boltzmann equation for both the ideal and a non-ideal fluid is
extended by adding Langevin noise terms in order to incorporate the effects of
thermal fluctuations. After casting the fluctuating discrete Boltzmann equation
in a form appropriate to the Onsager-Machlup theory of linear fluctuations, the
statistical properties of the noise are determined by invoking a
fluctuation-dissipation theorem at the kinetic level. By integrating the
fluctuating discrete Boltzmann equation, the fluctuating lattice Boltzmann
equation is obtained, which provides an efficient way to solve the equations of
fluctuating hydrodynamics for ideal and non-ideal fluids. Application of the
framework to a generic force-based non-ideal fluid model leads to ideal
gas-type thermal noise. Simulation results indicate proper thermalization of
all degrees of freedom.
| arxiv topic:physics.comp-ph cond-mat.soft physics.flu-dyn |
arxiv_dataset-23311012.3732 | Young Stars in the Time Domain: A Cool Stars 16 Splinter Summary
astro-ph.SR
Variability is a defining characteristic of young stellar systems, and
optical variability has been heavily studied to select and characterize the
photospheric properties of young stars. In recent years, multi-epoch
observations sampling a wider range of wavelengths and time-scales have
revealed a wealth of time-variable phenomena at work during the star formation
process. This splinter session was convened to summarize recent progress in
providing improved coverage and understanding of time-variable processes in
young stars and circumstellar disks. We begin by summarizing results from
several multi-epoch Spitzer campaigns, which have demonstrated that many young
stellar objects evidence significant mid-IR variability. While some of these
variations can be attributed to processes in the stellar photosphere, others
appear to trace short time-scale changes in the circumstellar disk which can be
successfully modeled with axisymmetric or non-axisymmetric structures. We also
review recent studies probing variability at shorter wavelengths that provide
evidence for high frequency pulsations associated with accretion outbursts,
correlated optical/X-ray variability in Classical T Tauri stars, and magnetic
reversals in young solar analogs.
| arxiv topic:astro-ph.SR |
arxiv_dataset-23321012.3832 | U(N) invariant dynamics for a simplified Loop Quantum Gravity model
gr-qc
The implementation of the dynamics in Loop Quantum Gravity (LQG) is still an
open problem. Here, we discuss a tentative dynamics for the simplest class of
graphs in LQG: Two vertices linked with an arbitrary number of edges. We use
the recently introduced U(N) framework in order to construct SU(2) invariant
operators and define a global U(N) symmetry that will select the
homogeneous/isotropic states. Finally, we propose a Hamiltonian operator
invariant under area-preserving deformations of the boundary surface and we
identify possible connections of this model with Loop Quantum Cosmology.
| arxiv topic:gr-qc |
arxiv_dataset-23331012.3932 | Balanced Interval Coloring
cs.DS
We consider the discrepancy problem of coloring $n$ intervals with $k$ colors
such that at each point on the line, the maximal difference between the number
of intervals of any two colors is minimal. Somewhat surprisingly, a coloring
with maximal difference at most one always exists. Furthermore, we give an
algorithm with running time $O(n \log n + kn \log k)$ for its construction.
This is in particular interesting because many known results for discrepancy
problems are non-constructive. This problem naturally models a load balancing
scenario, where $n$ tasks with given start- and endtimes have to be distributed
among $k$ servers. Our results imply that this can be done ideally balanced.
When generalizing to $d$-dimensional boxes (instead of intervals), a solution
with difference at most one is not always possible. We show that for any $d \ge
2$ and any $k \ge 2$ it is NP-complete to decide if such a solution exists,
which implies also NP-hardness of the respective minimization problem.
In an online scenario, where intervals arrive over time and the color has to
be decided upon arrival, the maximal difference in the size of color classes
can become arbitrarily high for any online algorithm.
| arxiv topic:cs.DS |
arxiv_dataset-23341012.4032 | A Type System for the Vectorial Aspect of the Linear-Algebraic
Lambda-Calculus
cs.LO
We describe a type system for the linear-algebraic lambda-calculus. The type
system accounts for the part of the language emulating linear operators and
vectors, i.e. it is able to statically describe the linear combinations of
terms resulting from the reduction of programs. This gives rise to an original
type theory where types, in the same way as terms, can be superposed into
linear combinations. We show that the resulting typed lambda-calculus is
strongly normalizing and features a weak subject-reduction.
| arxiv topic:cs.LO |
arxiv_dataset-23351012.4132 | Rationality of instanton moduli
math.AG
Tikhomirov (2009) proved the irreducibility of the moduli space of
mathematical instantons on the projective 3-space for all odd charges. The
irreducibility for charges between 1 and 5 was known before. In the present
paper, the rationality of the instanton moduli spaces is proved under the
assumption of the irreducibility. So, in particular, the instanton moduli
spaces are rational for all odd charges and for charges 2 and 4.
| arxiv topic:math.AG |
arxiv_dataset-23361012.4232 | Identification of a Wide, Low-Mass Multiple System Containing the Brown
Dwarf 2MASS J0850359+105716
astro-ph.SR
We report our discovery of NLTT 20346 as an M5+M6 companion system to the
tight binary (or triple) L dwarf 2MASS J0850359+105716. This nearby (~31 pc),
widely separated (~7700 AU) quadruple system was identified through a
cross-match of proper motion catalogs. Follow-up imaging and spectroscopy of
NLTT 20346 revealed it to be a magnetically active M5+M6 binary with components
separated by ~2" (50-80 AU). Optical spectroscopy of the components show only
moderate Halpha emission corresponding to a statistical age of ~5 - 7 Gyr for
both M dwarfs. However NLTT 20346 is associated with the XMM-Newton source
J085018.9+105644, and based on X-ray activity the age of NLTT 20346 is between
250-450 Myr. Strong Li absorption in the optical spectrum of 2MASS J0850+1057
indicates an upper age limit of 0.8 - 1.5 Gyr favoring the younger age for the
primary. Using evolutionary models in combination with an adopted system age of
0.25-1.5 Gyr indicates a total mass for 2MASS J0850+1057 of 0.07+/-0.02 Msun if
it is a binary. NLTT 20346/2MASS J0850+1057 joins a growing list of
hierarchical systems containing brown dwarf binaries and is among the lowest
binding energy associations found in the field. Formation simulations via
gravitational fragmentation of massive extended disks have successfully
produced a specific analog to this system.
| arxiv topic:astro-ph.SR |
arxiv_dataset-23371012.4332 | Quantum structural phase transition in chains of interacting atoms
cond-mat.stat-mech quant-ph
A quasi one--dimensional system of trapped, repulsively interacting atoms
(e.g., an ion chain) exhibits a structural phase transition from a linear chain
to a zigzag structure, tuned by reducing the transverse trap potential or
increasing the particle density. Since it is a one dimensional transition, it
takes place at zero temperature and therefore quantum fluctuations dominate. In
[Fishman, et al., Phys. Rev. B 77, 064111 (2008)] it was shown that the system
close to the linear-zigzag instability is described by a $\phi^4$ model. We
propose a mapping of the $\phi^4$ field theory to the well known Ising chain in
a transverse field, which exhibits a quantum critical point. Based on this
mapping, we estimate the quantum critical point in terms of the system
parameters. This estimate gives the critical value of the transverse trap
frequency for which the quantum phase transition occurs, and which has a
finite, measurable deviation from the critical point evaluated within the
classical theory. A measurement is suggested for atomic systems which can probe
the critical trap frequency at sufficiently low temperatures T. We focus in
particular on a trapped ion system, and estimate the implied limitations on T
and on the interparticle distance. We conclude that the experimental
observation of the quantum critical behavior is in principle accessible.
| arxiv topic:cond-mat.stat-mech quant-ph |
arxiv_dataset-23381012.4432 | The plasma emission model of RBS1774
astro-ph.SR
In the present paper we construct a self-consistent theory, interpreting the
observational properties of RBS1774. It is well known that the distribution
function of relativistic particles is one-dimensional at the pulsar surface.
However, cyclotron instability causes an appearance of transverse momenta of
relativistic electrons, which as a result, start to radiate in the synchrotron
regime. We study the process of the quasi-linear diffusion developed by means
of the cyclotron instability on the basis of the Vlasov's kinetic equation.
This mechanism provides generation of measured optical and X-ray emission on
the light cylinder lengthscales. A different approach of the synchrotron theory
is considered, giving the spectral energy distribution that is in a good
agreement with the XMM-Newton observational data. We also provide the possible
explanation of the spectral feature at 0.7keV, in the framework of the model.
| arxiv topic:astro-ph.SR |
arxiv_dataset-23391012.4532 | On union ultrafilters
math.LO math.GN
We present some new results on union ultrafilters. We characterize stability
for union ultrafilters and, as the main result, we construct a new kind of
unordered union ultrafilter.
| arxiv topic:math.LO math.GN |
arxiv_dataset-23401012.4632 | Quantum theory of fermion production after inflation
hep-ph hep-lat nucl-th
We show that quantum effects dramatically enhance the production of fermions
following preheating after inflation in the early Universe in the presence of
high excitations of bosonic quanta. As a consequence fermions rapidly approach
a quasistationary distribution with a thermal occupancy in the infrared, while
the inflaton enters a turbulent scaling regime. The failure of standard
semiclassical descriptions based on the Dirac equation with a homogeneous
background field is caused by nonperturbatively high boson occupation numbers.
During preheating the inflaton occupation number increases, thus leading to a
dynamical mechanism for the enhanced production of fermions from the
rescattering of the inflaton quanta. We comment on related phenomena in
heavy-ion collisions for the production of quark matter fields from highly
occupied gauge bosons.
| arxiv topic:hep-ph hep-lat nucl-th |
arxiv_dataset-23411012.4732 | Production of 26Al, 44Ti and 60Fe in Supernovae-sensitivity to the
helium burning rates
astro-ph.SR nucl-ex
We have studied the sensitivity of supernova production of the gamma emitting
nuclei 26Al, 44Ti and 60Fe to variations of the rates of the triple alpha and
12C(alpha, gamma) reactions. Over a range of twice their experimental
uncertainties we find variations in the production of 60Fe by more than a
factor of five. Smaller variations, about a factor of two to three, were
observed for 26Al and 44Ti. The yields of these isotopes change significantly
when the abundances of Lodders (2003) are used instead of those of Anders and
Grevesse (1989). These sensitivities will limit conclusions based on a
comparison of observed gamma ray intensities and stellar models until the
helium burning rates are better known. Prospects for improving the helium
burning rates are discussed and a new version of the Boyes rate for 12C(alpha,
gamma} is presented.
| arxiv topic:astro-ph.SR nucl-ex |
arxiv_dataset-23421012.4832 | Surfaces with $p_g = q= 1$, $K^2 = 7$ and non-birational bicanonical
mpas
math.AG
Let $S$ be a minimal surface of general type with $p_g = q = 1, K_S^2 = 7$.
We prove that the degree of the bicanonical map is 1 or 2. Furthermore, if the
degree is 2, we describe $S$ by a double cover.
| arxiv topic:math.AG |
arxiv_dataset-23431012.4932 | Pressure-induced phase transition of Bi2Te3 into the bcc structure
cond-mat.mtrl-sci cond-mat.supr-con
The pressure-induced phase transition of bismuth telluride, Bi2Te3, has been
studied by synchrotron x-ray diffraction measurements at room temperature using
a diamond-anvil cell (DAC) with loading pressures up to 29.8 GPa. We found a
high-pressure body-centered cubic (bcc) phase in Bi2Te3 at 25.2 GPa, which is
denoted as phase IV, and this phase apperars above 14.5 GPa. Upon releasing the
pressure from 29.8 GPa, the diffraction pattern changes with pressure
hysteresis. The original rhombohedral phase is recovered at 2.43 GPa. The bcc
structure can explain the phase IV peaks. We assumed that the structural model
of phase IV is analogous to a substitutional binary alloy; the Bi and Te atoms
are distributed in the bcc-lattice sites with space group Im-3m. The results of
Rietveld analysis based on this model agree well with both the experimental
data and calculated results. Therefore, the structure of phase IV in Bi2Te3 can
be explained by a solid solution with a bcc lattice in the Bi-Te (60 atomic%
tellurium) binary system.
| arxiv topic:cond-mat.mtrl-sci cond-mat.supr-con |
arxiv_dataset-23441012.5032 | Tree-level Recursion Relation and Dual Superconformal Symmetry of the
ABJM Theory
hep-th
We propose a recursion relation for tree-level scattering amplitudes in
three-dimensional Chern-Simons-matter theories. The recursion relation involves
a complex deformation of momenta which generalizes the BCFW-deformation used in
higher dimensions. Using background field methods, we show that all tree-level
superamplitudes of the ABJM theory vanish for large deformations, establishing
the validity of the recursion formula. Furthermore, we use the recursion
relation to compute six-point and eight-point component amplitudes and match
them with independent computations based on Feynman diagrams or the
Grassmannian integral formula. As an application of the recursion relation, we
prove that all tree-level amplitudes of the ABJM theory have dual
superconformal symmetry. Using generalized unitarity methods, we extend this
symmetry to the cut-constructible parts of the loop amplitudes.
| arxiv topic:hep-th |
arxiv_dataset-23451012.5132 | Single top quark production and decay in the t-channel at
next-to-leading order at the LHC
hep-ph
We present a study of single top and single antitop quark production in the
t-channel mode at the LHC pp collider at 7 TeV, 10 TeV and 14 TeV, including
next-to-leading order QCD corrections to the production and decay of the top
quark. We discuss the effects of different O(alpha_s) contributions on the
inclusive cross section and important kinematic distributions, after imposing
the relevant cuts to select t-channel single top quark events.
| arxiv topic:hep-ph |
arxiv_dataset-23461012.5232 | Orbit determination of space objects based on sparse optical data
physics.space-ph math-ph math.MP
While building up a catalog of Earth orbiting objects, if the available
optical observations are sparse, not deliberate follow ups of specific objects,
no orbit determination is possible without previous correlation of observations
obtained at different times. This correlation step is the most computationally
intensive, and becomes more and more difficult as the number of objects to be
discovered increases. In this paper we tested two different algorithms (and the
related prototype software) recently developed to solve the correlation problem
for objects in geostationary orbit (GEO), including the accurate orbit
determination by full least squares solutions with all six orbital elements.
Because of the presence in the GEO region of a significant subpopulation of
high area to mass objects, strongly affected by non-gravitational
perturbations, it was actually necessary to solve also for dynamical parameters
describing these effects, that is to fit between 6 and 8 free parameters for
each orbit. The validation was based upon a set of real data, acquired from the
ESA Space Debris Telescope (ESASDT) at the Teide observatory (Canary Islands).
We proved that it is possible to assemble a set of sparse observations into a
set of objects with orbits, starting from a sparse time distribution of
observations, which would be compatible with a survey capable of covering the
region of interest in the sky just once per night. This could result in a
significant reduction of the requirements for a future telescope network, with
respect to what would have been required with the previously known algorithm
for correlation and orbit determination.
| arxiv topic:physics.space-ph math-ph math.MP |
arxiv_dataset-23471012.5332 | Frustrated Total Internal Reflection: Resonant and Negative
Goos-H\"anchen Shifts in Microwave Regime
physics.optics physics.plasm-ph
It is well-known that the variations of Goos-H\"anchen shifts (GHSs) are
closely associated with the enengy-flux provided by evanescent states in the
case of total internal reflection. However, when the frustrated internal total
reflection (FTIR) is realized with a Polymethyl Methacrylate (PMMA)
double-prism system operated in the microwave frequency range of 8.2 GHz to
12.4 GHz, we observe that the GH shifts for the reflected beam show periodic
resonances with varying the operation frequency or the air layer thickness,
which is different from the variation of the corresponding reflected energy.
Moreover, in another FTIR based system introduced by a composite absorptive
material slab with a two-dimensional top layer of frequency selective surface
(FSS), the GHSs for reflected beam are discovered as not only resonant but also
negative with the incidence of transverse electric that is TE polarized.
| arxiv topic:physics.optics physics.plasm-ph |
arxiv_dataset-23481012.5432 | Towards Topological Quantum Computation? - Knotting and Fusing Flux
Tubes
quant-ph cond-mat.other hep-th math-ph math.MP math.RT
Models for topological quantum computation are based on braiding and fusing
anyons (quasiparticles of fractional statistics) in (2+1)-D. The anyons that
can exist in a physical theory are determined by the symmetry group of the
Hamiltonian. In the case that the Hamiltonian undergoes spontaneous symmetry
breaking of the full symmetry group G to a finite residual gauge group H,
particles are given by representations of the quantum double $D(H)$ of the
subgroup. The quasi-triangular Hopf Algebra D(H) is obtained from Drinfeld's
quantum double construction applied to the algebra F(H) of functions on the
finite group H.
A major new contribution of this work is a program written in MAGMA to
compute the particles (and their properties - including spin) that can exist in
a system with an arbitrary finite residual gauge group, in addition to the
braiding and fusion rules for those particles. We compute explicitly the fusion
rules for two non-abelian group doubles suggested for universal quantum
computation: $S_3$ and $A_5$, and discover some interesting results,
subsystems, and symmetries in the tables. SO(3)_4 (the restriction of
Chern-Simons theory $SU(2)_4$) and its mirror image are discovered as
3-particle subsystems in the 8-particle $S_3$ quantum double. The tables
demonstrate that both $S_3$ and $A_5$ anyons are all Majorana, but this is not
the case for all finite groups. In the appendices, the quantum doubles for the
remaining nonabelian subgroups of SO(3) - $S_4$, $A_4$, and $D_4$ (the second
in the infinite family $D_n$) - are tabulated and analyzed. In addition, the
probabilities of obtaining any given fusion product in quantum computation
applications are determined and programmed in MAGMA. Throughout, connections to
possible experiments are mentioned.
| arxiv topic:quant-ph cond-mat.other hep-th math-ph math.MP math.RT |
arxiv_dataset-23491012.5532 | Thermodynamics of Modified Chaplygin Gas and Tachyonic Field
physics.gen-ph
Here we generalize the results of the work of ref. [10] in modified Chaplygin
gas model and tachyonic field model. Here we have studied the thermodynamical
behaviour and the equation of state in terms of volume and temperature for both
models. We have used the solution and the corresponding equation of state of
our previous work [12] for tachyonic field model. We have also studied the
thermodynamical stability using thermal equation of state for the tachyonic
field model and have shown that there is no critical points during
thermodynamical expansion. The determination of $T_{*}$ due to expansion for
the tachyonic field have been discussed by assuming some initial conditions.
Here, the thermal quantities have been investigated using some reduced
parameters.
| arxiv topic:physics.gen-ph |
arxiv_dataset-23501012.5632 | Quantum dynamics of a vibrational mode of a membrane within an optical
cavity
quant-ph cond-mat.mes-hall physics.optics
Optomechanical systems are a promising candidate for the implementation of
quantum interfaces for storing and redistributing quantum information. Here we
focus on the case of a high-finesse optical cavity with a thin vibrating
semitransparent membrane in the middle. We show that robust and stationary
optomechanical entanglement could be achieved in the system, even in the
presence of nonnegligible optical absorption in the membrane. We also present
some preliminary experimental data showing radiation-pressure induced optical
bistability.
| arxiv topic:quant-ph cond-mat.mes-hall physics.optics |
arxiv_dataset-23511012.5732 | Brewing moonshine for Mathieu
math.NT hep-th math.RT
We propose a moonshine for the sporadic Mathieu group M_12 that relates its
conjugacy classes to various modular forms and Borcherds Kac-Moody Lie
superalgebras.
| arxiv topic:math.NT hep-th math.RT |
arxiv_dataset-23521012.5832 | On the Existence of Bertrand-Nash Equilibrium Prices Under Logit Demand
q-fin.GN cs.GT
This article presents a proof of the existence of Bertrand-Nash equilibrium
prices with multi-product firms and under the Logit model of demand that does
not rely on restrictive assumptions on product characteristics, firm
homogeneity or symmetry, product costs, or linearity of the utility function.
The proof is based on conditions for the indirect utility function, fixed-point
equations derived from the first-order conditions, and a direct analysis of the
second-order conditions resulting in the uniqueness of profit-maximizing
prices. Several subsequent results also demonstrate that price equilibrium
under the Logit model of demand cannot adequately describe multi-product
pricing.
| arxiv topic:q-fin.GN cs.GT |
arxiv_dataset-23531012.5932 | An statistical analysis of stratification and inequity in the income
distribution
q-fin.GN q-fin.ST
The analysis of the USA 2001 income distribution shows that it can be
described by at least two main components, which obey the generalized Tsallis
statistics with different values of the q parameter. Theoretical calculations
using the gas kinetics model with a distributed saving propensity factor and
two ensembles reproduce the empirical data and provide further information on
the structure of the distribution, which shows a clear stratification. This
stratification is amenable to different interpretations, which are analyzed.
The distribution function is invariant with the average individual income,
which implies that the inequity of the distribution cannot be modified by
increasing the total income.
| arxiv topic:q-fin.GN q-fin.ST |
arxiv_dataset-23541012.6032 | Local Integrals for Planar Scattering Amplitudes
hep-th
Recently, an explicit, recursive formula for the all-loop integrand of planar
scattering amplitudes in N=4 SYM has been described, generalizing the BCFW
formula for tree amplitudes, and making manifest the Yangian symmetry of the
theory. This has made it possible to easily study the structure of multi-loop
amplitudes in the theory. In this paper we describe a remarkable fact revealed
by these investigations: the integrand can be expressed in an amazingly simple
and manifestly local form when represented in momentum-twistor space using a
set of chiral integrals with unit leading singularities. As examples, we
present very-concise expressions for all 2- and 3-loop MHV integrands, as well
as all 2-loop NMHV integrands. We also describe a natural set of manifestly
IR-finite integrals that can be used to express IR-safe objects such as the
ratio function. Along the way we give a pedagogical introduction to the
foundations of the subject. The new local forms of the integrand are closely
connected to leading singularities---matching only a small subset of all
leading singularities remarkably suffices to determine the full integrand.
These results strongly suggest the existence of a theory for the integrand
directly yielding these local expressions, allowing for a more direct
understanding of the emergence of local spacetime physics.
| arxiv topic:hep-th |
arxiv_dataset-23551101.0087 | Update on the status of Hadronic Squeezed Correlations at RHIC Energies
nucl-th
In high energy heavy ion collisions a hot and dense medium is formed, where
the hadronic masses may be shifted from their asymptotic values. If this mass
modification occurs, squeezed back-to-back correlations (BBC) of
particle-antiparticle pairs are predicted to appear, both in the femionic
(fBBC) and in the bosonic (bBBC) sectors. Although they have unlimited
intensity even for finite-size expanding systems, these hadronic squeezed
correlations are very sensitive to their time emission distribution. Here we
discuss results in case this time emission is parameterized by a Levy-type
distribution, showing that it reduces the signal even more dramatically than a
Lorentzian distribution, which already reduces the intensity of the effect by
orders of magnitude, as compared to the sudden emission. However, we show that
the signal could still survive if the duration of the process is short, and if
the effect is searched for lighter mesons, such as kaons. We compare some of
our results to recent PHENIX preliminary data on squeezed correlations of
K^+K^- pairs.
| arxiv topic:nucl-th |
arxiv_dataset-23561101.0187 | Boundary correlation functions of the six and nineteen vertex models
with domain wall boundary conditions
math-ph cond-mat.stat-mech math.MP
Correlation functions of the six and nineteen vertex models on an N \times N
lattice with domain wall boundary conditions are studied. The general
expression of the boundary correlation functions is obtained for the six vertex
model by use of the quantum inverse scattering method. The correlation
functions which are not "boundary" can be expressed as a linear sum of the
boundary correlation functions. For the nineteen vertex model, the boundary
correlation functions are shown to be expressed in terms of those for the six
vertex model.
| arxiv topic:math-ph cond-mat.stat-mech math.MP |
arxiv_dataset-23571101.0287 | On the Capacity of the Heat Channel, Waterfilling in the Time-Frequency
Plane, and a C-NODE Relationship
cs.IT math.IT
The heat channel is defined by a linear time-varying (LTV) filter with
additive white Gaussian noise (AWGN) at the filter output. The continuous-time
LTV filter is related to the heat kernel of the quantum mechanical harmonic
oscillator, so the name of the channel. The channel's capacity is given in
closed form by means of the Lambert W function. Also a waterfilling theorem in
the time-frequency plane for the capacity is derived. It relies on a specific
Szego theorem for which an essentially self-contained proof is provided.
Similarly, the rate distortion function for a related nonstationary source is
given in closed form and a (reverse) waterfilling theorem in the time-frequency
plane is derived. Finally, a second closed-form expression for the capacity of
the heat channel based on the detected perturbed filter output signals is
presented. In this context, a precise differential connection between channel
capacity and the normalized optimal detection error (NODE) is revealed. This
C-NODE relationship is compared with the well-known I-MMSE relationship
connecting mutual information with the minimum mean-square error (MMSE) of
estimation theory.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-23581101.0387 | MCMC Using Ensembles of States for Problems with Fast and Slow Variables
such as Gaussian Process Regression
stat.CO
I introduce a Markov chain Monte Carlo (MCMC) scheme in which sampling from a
distribution with density pi(x) is done using updates operating on an
"ensemble" of states. The current state x is first stochastically mapped to an
ensemble, x^{(1)},...,x^{(K)}. This ensemble is then updated using MCMC updates
that leave invariant a suitable ensemble density, rho(x^{(1)},...,x^{(K)}),
defined in terms of pi(x^{(i)}) for i=1,...,K. Finally a single state is
stochastically selected from the ensemble after these updates. Such ensemble
MCMC updates can be useful when characteristics of pi and the ensemble permit
pi(x^{(i)}) for all i in {1,...,K}, to be computed in less than K times the
amount of computation time needed to compute pi(x) for a single x. One common
situation of this type is when changes to some "fast" variables allow for quick
re-computation of the density, whereas changes to other "slow" variables do
not. Gaussian process regression models are an example of this sort of problem,
with an overall scaling factor for covariances and the noise variance being
fast variables. I show that ensemble MCMC for Gaussian process regression
models can indeed substantially improve sampling performance. Finally, I
discuss other possible applications of ensemble MCMC, and its relationship to
the "multiple-try Metropolis" method of Liu, Liang, and Wong and the "multiset
sampler" of Leman, Chen, and Lavine.
| arxiv topic:stat.CO |
arxiv_dataset-23591101.0487 | Observation of a first order phase transition in fluid iron at pressures
of 3 to 5 GPa
cond-mat.other
Direct measurements of resistivity and caloric equation of state have been
performed for fluid iron at pressures of 2 to 12 GPa in a wide density range.
We found that the isochoric temperature coefficient of resistivity becomes
negative, and this is considered as an indication of the metal-to-nonmetal
transition, when density decreased by a factor of 3 to 4 compared to the normal
solid density. We detected also that isentropes plotted in the pressure -
specific volume plane have well-defined kinks localized on a convex curve with
a maximum at about 5 GPa. Such behavior of isentropes evidences about a first
order phase transition with a critical pressure one order of magnitude higher
than the predicted pressure of the liquid-vapor critical point. Arguments are
presented that the observed phase transition is most likely the liquid-vapor
transition rather than an extra first order transition in the fluid state. We
show that the gaseous nonmetallic phase represents dense plasma in the 1-2-th
state of ionization so that it is a plasma phase transition as well.
| arxiv topic:cond-mat.other |
arxiv_dataset-23601101.0587 | Non conforming vector finite elements for H(curl) intersected with
H(div)
math.NA math.AP
We present a family of nonconforming vector finite elements of arbitrary
order for problems posed on the space (curl) intersected with H(div) on a
bidimensional domain. This result was first stated as a conjecture by Brenner
and Sung. In contrast an extension of the same conjecture to three dimensional
domains is disproved.
| arxiv topic:math.NA math.AP |
arxiv_dataset-23611101.0687 | Investigations of a compartmental model for leucine kinetics using
nonlinear mixed effects models with ordinary and stochastic differential
equations
q-bio.QM
Nonlinear mixed effects models represent a powerful tool to simultaneously
analyze data from several individuals. In this study a compartmental model of
leucine kinetics is examined and extended with a stochastic differential
equation to model non-steady state concentrations of free leucine in the
plasma. Data obtained from tracer/tracee experiments for a group of healthy
control individuals and a group of individuals suffering from diabetes mellitus
type 2 are analyzed. We find that the interindividual variation of the model
parameters is much smaller for the nonlinear mixed effects models, compared to
traditional estimates obtained from each individual separately. Using the mixed
effects approach, the population parameters are estimated well also when only
half of the data are used for each individual. For a typical individual the
amount of free leucine is predicted to vary with a standard deviation of 8.9%
around a mean value during the experiment. Moreover, leucine degradation and
protein uptake of leucine is smaller, proteolysis larger, and the amount of
free leucine in the body is much larger for the diabetic individuals than the
control individuals. In conclusion nonlinear mixed effects models offers
improved estimates for model parameters in complex models based on
tracer/tracee data and may be a suitable tool to reduce data sampling in
clinical studies.
| arxiv topic:q-bio.QM |
arxiv_dataset-23621101.0787 | Multiplicities in ultrarelativistic proton-(anti)proton collisions and
negative binomial distribution fits
hep-ph hep-ex physics.data-an
Likelihood ratio tests are performed for the hypothesis that charged-particle
multiplicities measured in proton-(anti)proton collisions at $\sqrt{s}$ = 0.9
and 2.36 TeV are distributed according to the negative binomial form. Results
indicate that the hypothesis should be rejected in the all cases of ALICE-LHC
measurements in the limited pseudo-rapidity windows, whereas should be accepted
in the corresponding cases of UA5 data. Possible explanations of that and of
the disagreement with the least-squares fitting method are given.
| arxiv topic:hep-ph hep-ex physics.data-an |
arxiv_dataset-23631101.0887 | Cascades damage in {\alpha}-iron with high damage energy
cond-mat.mtrl-sci
We present a numerical study of the cascades damage in {\alpha}-iron for high
cascade energy up to 250keV, corresponding to neutron energy above and beyond
14.1MeV. We observe that Frenkel pairs production efficiency and perfect
crystal lattices damage efficiency have the close trend within the statistical
uncertainty versus cascade energy, and the two kinds of curves first decrease
with power-law trend, and arrive at their minimum at threshold energy of
subcascades, then these curves begin to increase with cascade energy. The
analysis demonstrates that the tendency of these curves reflects degree of
concentration of defects and depends on the number of subcascades which keeps
identical with defects scattering and the energy of subcascades reflecting
defects concentration. The pair analysis technique may help us understand the
total damage of perfect crystal lattices.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-23641101.0987 | Dynamic Red Queen explains patterns in fatal insurgent attacks
physics.soc-ph cond-mat.stat-mech q-bio.PE
The Red Queen's notion "It takes all the running you can do, to keep in the
same place" has been applied within evolutionary biology, politics and
economics. We find that a generalized version in which an adaptive Red Queen
(e.g. insurgency) sporadically edges ahead of a Blue King (e.g. military),
explains the progress curves for fatal insurgent attacks against the coalition
military within individual provinces in Afghanistan and Iraq. Remarkably
regular mathematical relations emerge which suggest a prediction formula for
the timing of the n'th future fatal day, and provide a common framework for
understanding how insurgents fight in different regions. Our findings are
consistent with a Darwinian selection hypothesis which favors a weak species
which can adapt rapidly, and establish an unexpected conceptual connection to
the physics of correlated walks.
| arxiv topic:physics.soc-ph cond-mat.stat-mech q-bio.PE |
arxiv_dataset-23651101.1087 | On the Inclination Dependence of Exoplanet Phase Signatures
astro-ph.EP
Improved photometric sensitivity from space-based telescopes have enabled the
detection of phase variations for a small sample of hot Jupiters. However,
exoplanets in highly eccentric orbits present unique opportunities to study the
effects of drastically changing incident flux on the upper atmospheres of giant
planets. Here we expand upon previous studies of phase functions for these
planets at optical wavelengths by investigating the effects of orbital
inclination on the flux ratio as it interacts with the other effects induced by
orbital eccentricity. We determine optimal orbital inclinations for maximum
flux ratios and combine these calculations with those of projected separation
for application to coronagraphic observations. These are applied to several of
the known exoplanets which may serve as potential targets in current and future
coronagraph experiments.
| arxiv topic:astro-ph.EP |
arxiv_dataset-23661101.1187 | Multi-Messenger Astrophysics with IceCube
astro-ph.HE
The cubic kilometer IceCube neutrino telescope now operating at the South
Pole in a near complete configuration observes the neutrino sky with an
unprecedented sensitivity to galactic and extra-galactic cosmic ray
accelerators. Within the multi-messenger framework, IceCube offers unique
capabilities to correlate and contrast the neutrino sky with the gamma-ray sky
and ultra high energy cosmic rays and complements other indirect and direct
dark matter search programs. We review here the status of the experiment and
recent selected results. A discussion of the implications of the observations
will be followed by the prospects of future developments, substantially
extending the reach of the observatory at extremely high energies, in the GZK
region and at low energies enhancing capabilities to probe dark matter and
cosmic ray sources in the southern sky.
| arxiv topic:astro-ph.HE |
arxiv_dataset-23671101.1287 | Macroscopic model of self-propelled bacteria swarming with regular
reversals
physics.bio-ph nlin.CD q-bio.CB
Periodic reversals of the direction of motion in systems of self-propelled
rod shaped bacteria enable them to effectively resolve traffic jams formed
during swarming and maximize their swarming rate. In this paper, a connection
is found between a microscopic one dimensional cell-based stochastic model of
reversing non-overlapping bacteria and a macroscopic non-linear diffusion
equation describing dynamics of the cellular density. Boltzmann-Matano analysis
is used to determine the nonlinear diffusion equation corresponding to the
specific reversal frequency. Macroscopically (ensemble-vise) averaged
stochastic dynamics is shown to be in a very good agreement with the numerical
solutions of the nonlinear diffusion equation. Critical density $p_0$ is
obtained such that nonlinear diffusion is dominated by the collisions between
cells for the densities $p>p_0$. An analytical approximation of the pairwise
collision time and semi-analytical fit for the total jam time per reversal
period are also obtained. It is shown that cell populations with high reversal
frequencies are able to spread out effectively at high densities. If the cells
rarely reverse then they are able to spread out at lower densities but are less
efficient at spreading out at at higher densities.
| arxiv topic:physics.bio-ph nlin.CD q-bio.CB |
arxiv_dataset-23681101.1387 | Work Function of Single-wall Silicon Carbide Nanotube
cond-mat.mes-hall
Using first-principles calculations, we study the work function of single
wall silicon carbide nanotube (SiCNT). The work function is found to be highly
dependent on the tube chirality and diameter. It increases with decreasing the
tube diameter. The work function of zigzag SiCNT is always larger than that of
armchair SiCNT. We reveal that the difference between the work function of
zigzag and armchair SiCNT comes from their different intrinsic electronic
structures, for which the singly degenerate energy band above the Fermi level
of zigzag SiCNT is specifically responsible. Our finding offers potential
usages of SiCNT in field-emission devices.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-23691101.1487 | Colloids in Cholesterics: Size-Dependent Defects and Non-Stokesian
Microrheology
cond-mat.soft cond-mat.mtrl-sci physics.flu-dyn
We simulate a colloidal particle (radius R) in a cholesteric liquid crystal
(pitch p) with tangential order parameter alignment at the particle surface.
The local defect structure evolves from a dipolar pair of surface defects
(boojums) at small R/p to a pair of twisted disclination lines wrapping around
the particle at larger values. On dragging the colloid with small velocity v
through the medium along the cholesteric helix axis (an active microrheology
measurement), we find a hydrodynamic drag force that scales linearly with v but
superlinearly with R-in striking violation of Stokes' law, as generally used to
interpret such measurements.
| arxiv topic:cond-mat.soft cond-mat.mtrl-sci physics.flu-dyn |
arxiv_dataset-23701101.1587 | Adaptive and anisotropic piecewise polynomial approximation
math.NA
We survey the main results of approximation theory for adaptive piecewise
polynomial functions. In such methods, the partition on which the piecewise
polynomial approximation is defined is not fixed in advance, but adapted to the
given function f which is approximated. We focus our discussion on (i) the
properties that describe an optimal partition for f, (ii) the smoothness
properties of f that govern the rate of convergence of the approximation in the
Lp-norms, and (iii) fast refinement algorithms that generate near optimal
partitions. While these results constitute a fairly established theory in the
univariate case and in the multivariate case when dealing with elements of
isotropic shape, the approximation theory for adaptive and anisotropic elements
is still building up. We put a particular emphasis on some recent results
obtained in this direction.
| arxiv topic:math.NA |
arxiv_dataset-23711101.1687 | Crystal bases and Newton-Okounkov bodies
math.AG math.RT
Let G be a connected reductive algebraic group. We prove that the string
parametrization of a crystal basis for a finite dimensional irreducible
representation of G extends to a natural valuation on the field of rational
functions on the flag variety G/B, which is a highest term valuation
corresponding to a coordinate system on a Bott-Samelson variety. This shows
that the string polytopes associated to irreducible representations, can be
realized as Newton-Okounkov bodies for the flag variety. This is closely
related to an earlier result of A. Okounkov for the Gelfand-Cetlin polytopes of
the symplectic group. As a corollary we recover a multiplicativity property of
the canonical basis due to P. Caldero. We generalize the results to spherical
varieties. From these the existence of SAGBI bases for the homogeneous
coordinate rings of flag and spherical varieties, as well as their toric
degenerations follow, recovering previous results of Caldero, Alexeev-Brion and
the author.
| arxiv topic:math.AG math.RT |
arxiv_dataset-23721101.1787 | An optical spectroscopic survey of the 3CR sample of radio galaxies with
z<0.3. IV. Discovery of the new spectroscopic class of relic radio galaxies
astro-ph.CO
From an optical spectroscopic survey of 3CR radio galaxies with z<0.3, we
discovered a new spectroscopic class of powerful radio-loud AGN. The defining
characteristics of these galaxies are that compared with radio galaxies of
similar radio luminosity they have: a [O III]\Hb ratio of ~0.5, indicative of
an extremely low level of gas excitation; a large deficit of [O III] emission
and radio core power. We interpret these objects as relic AGN, i.e. sources
that experienced a large drop in their level of nuclear activity, causing a
decrease in their nuclear and line luminosity. This class opens a novel
approach to investigating lifetimes and duty cycles of AGN.
| arxiv topic:astro-ph.CO |
arxiv_dataset-23731101.1887 | Relativistic plasma and ICM/radio source interaction
astro-ph.HE
The first detection of a diffuse radio source in a cluster of galaxies, dates
back to the 1959 (Coma Cluster, Large et al. 1959). Since then, synchrotron
radiating radio sources have been found in several clusters, and represent an
important cluster component which is linked to the thermal gas. Such sources
indicate the existence of large scale magnetic fields and of a population of
relativistic electrons in the cluster volume. The observational results provide
evidence that these phenomena are related to turbulence and shock-structures in
the intergalactic medium, thus playing a major role in the evolution of the
large scale structure in the Universe. The interaction between radio sources
and cluster gas is well established in particular at the center of cooling core
clusters, where feedback from AGN is a necessary ingredient to adequately
describe the formation and evolution of galaxies and host clusters.
| arxiv topic:astro-ph.HE |
arxiv_dataset-23741101.1987 | Neutrino Mixing and the Double Tetrahedral Group
hep-ph
In the spirit of a previous study of the tetrahedral group $T \simeq A_4$, we
discuss a minimalist scheme to derive the neutrino mixing matrix using the
double tetrahedral group $T'$, the double cover of $T$. The new features are
three distinct 2-dimensional representations and complex Clebsch-Gordan
coefficients, which can result in a geometric source of CP violation in the
neutrino mass matrix. In an appendix, we derive explicitly the relevant group
theory for the tetrahedral group $T$ and its double cover $T'$.
| arxiv topic:hep-ph |
arxiv_dataset-23751101.2087 | Using Stellar Densities to Evaluate Transiting Exoplanetary Candidates
astro-ph.EP
One of the persistent complications in searches for transiting exoplanets is
the low percentage of the detected candidates that ultimately prove to be
planets, which significantly increases the load on the telescopes used for the
follow-up observations to confirm or reject candidates. Several attempts have
been made at creating techniques that can pare down candidate lists without the
need of additional observations. Some of these techniques involve a detailed
analysis of light curve characteristics; others estimate the stellar density or
some proxy thereof. In this paper, we extend upon this second approach,
exploring the use of independently-calculated stellar densities to identify the
most promising transiting exoplanet candidates. We use a set of CoRoT
candidates and the set of known transiting exoplanets to examine the potential
of this approach. In particular, we note the possibilities inherent in the
high-precision photometry from space missions, which can detect stellar
asteroseismic pulsations from which accurate stellar densities can be extracted
without additional observations.
| arxiv topic:astro-ph.EP |
arxiv_dataset-23761101.2187 | Evidence for a spin-aligned neutron-proton paired phase from the level
structure of $^{92}$Pd
nucl-ex nucl-th
The general phenomenon of shell structure in atomic nuclei has been
understood since the pioneering work of Goeppert-Mayer, Haxel, Jensen and
Suess.They realized that the experimental evidence for nuclear magic numbers
could be explained by introducing a strong spin-orbit interaction in the
nuclear shell model potential. However, our detailed knowledge of nuclear
forces and the mechanisms governing the structure of nuclei, in particular far
from stability, is still incomplete. In nuclei with equal neutron and proton
numbers ($N = Z$), the unique nature of the atomic nucleus as an object
composed of two distinct types of fermions can be expressed as enhanced
correlations arising between neutrons and protons occupying orbitals with the
same quantum numbers. Such correlations have been predicted to favor a new type
of nuclear superfluidity; isoscalar neutron-proton pairing, in addition to
normal isovector pairing (see Fig. 1). Despite many experimental efforts these
predictions have not been confirmed. Here, we report on the first observation
of excited states in $N = Z = 46$ nucleus $^{92}$Pd. Gamma rays emitted
following the $^{58}$Ni($^{36}$Ar,2$n$)$^{92}$Pd fusion-evaporation reaction
were identified using a combination of state-of-the-art high-resolution
{\gamma}-ray, charged-particle and neutron detector systems. Our results reveal
evidence for a spin-aligned, isoscalar neutron-proton coupling scheme,
different from the previous prediction. We suggest that this coupling scheme
replaces normal superfluidity (characterized by seniority coupling) in the
ground and low-lying excited states of the heaviest N = Z nuclei. The strong
isoscalar neutron- proton correlations in these $N = Z$ nuclei are predicted to
have a considerable impact on their level structures, and to influence the
dynamics of the stellar rapid proton capture nucleosynthesis process.
| arxiv topic:nucl-ex nucl-th |
arxiv_dataset-23771101.2287 | Stability beyond the neutron drip-line near the third peak of the
r-process nucleosynthesis
nucl-th astro-ph.SR nucl-ex
We have investigated the nuclear shell effects at N=126 in the region of the
third peak of the r-process nucleosynthesis within the framework of the
relativistic mean-field theory using the Lagrangian model NL-SV1 with the
vector self-coupling of omega-meson. Our study encompasses even-even nuclei
with N=110-140 in the isotopic chains of Hf (Z=72) down to Ba (Z=56). It is
shown that the nuclear shell effects at N=126 remain strong even as one moves
far away from the line of the beta-stability. As the neutron drip line
approaches N=126, nuclei exhibit vanishingly small neutron separation energy.
However, going beyond the neutron drip line, we observe an interesting feature
in that some nuclei near N ~ 132-134 for the isotopic chains of Z=62-68 show
enhanced neutron separation energy. This is especially pronounced for the
isotopes of Gd (Z=64) and Dy (Z=66). These nuclei exhibit the phenomenon of
stability beyond the neutron drip line. Our analysis of the single-particle
spectrum shows that this is engendered by the deformation assumed by these
nuclei with the consequence that the neutron single-particle spectrum is pushed
down in energy, thus leading to enhanced stability beyond the drip line.
| arxiv topic:nucl-th astro-ph.SR nucl-ex |
arxiv_dataset-23781101.2387 | Scaling of Transport Coefficients of Porous Media under Compaction
physics.flu-dyn cond-mat.stat-mech physics.geo-ph
Porous sediments in geological systems are exposed to stress by the
above-laying mass and consequent compaction, which may be significantly
nonuniform across the massif. We derive scaling laws for the compaction of
sediments of similar geological origin. With these laws, we evaluate the
dependence of the transport properties of a fluid-saturated porous medium
(permeability, effective molecular diffusivity, hydrodynamic dispersion,
electrical and thermal conductivities) on its porosity. In particular, we
demonstrate that the assumption of a uniform geothermal gradient is not
adequate for systems with nonuniform compaction and show the importance of the
derived scaling laws for mathematical modelling of methane hydrate deposits;
these deposits are believed to have potential for impact on global climate
change and Glacial-Interglacial cycles.
| arxiv topic:physics.flu-dyn cond-mat.stat-mech physics.geo-ph |
arxiv_dataset-23791101.2487 | Enhanced thermoelectric properties of coaxial Bi2Te3/Sb2Te3
nanostructures studied by theoretical modeling
cond-mat.mtrl-sci
Critical thermoelectric parameters including Seebeck coefficient, electrical
conductivity, thermal conductivity and figure of merit ZT of one-dimensional
coaxial Bi2Te3/Sb2Te3 nanocomposite were modeled by following the single
carrier pocket and sharp interface assumptions. A calculation scheme based on
Landauer approach, instead of commonly used Boltzmann transport equation (BTE)
with relaxation time approximation, was adopted to numerically obtain the
transmission functions which can be used to evaluate thermoelectric properties.
Considerable enhancement of ZT was obtained through our modeling and numerical
calculation, and the corresponding dependence of thermoelectric performance on
structure parameters was studied. Finally, the efficiency at the maximum power
condition for this 1-D system was also investigated.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-23801101.2587 | Radial projections of rectifiable sets
math.CA
We show that if no $m$-plane contains almost all of an $m$-rectifiable set $E
\subset \R^{n}$, then there exists a single $(m - 1)$-plane $V$ such that the
radial projection of $E$ has positive $m$-dimensional measure from every point
outside $V$.
| arxiv topic:math.CA |
arxiv_dataset-23811101.2687 | High energy gamma-ray properties of the FR I radio galaxy NGC 1275
astro-ph.HE
We report on our study of the high-energy $\gamma-$ray emission from the FR I
radio galaxy NGC 1275, based on two years of observations with the Fermi-LAT
detector. Previous Fermi studies of NGC 1275 had found evidence for spectral
and flux variability on monthly timescales during the first year of Fermi-LAT
observations. This variability is also seen in the larger two year data set,
during which we observe a large $\gamma-$ray flare (June-August 2010). The
increased photon statistics from this large flare have allowed the discovery of
flux variability from NGC 1275 on the timescales of days. The largest flux
variation observed during this flare being a factor of $\sim 3$ from one day to
the next and a resultant $e$-folding risetime of $1.51\pm0.2$ days. The two
year averaged $E>$100 MeV $\gamma-$ray spectrum is adequately described by a
power-law spectrum, with a photon index, $\Gamma$, of $2.09 \pm 0.02$, and a
resultant integrated flux of $F_{\gamma}=(2.2\pm0.1) \times 10^{-7}$ ph
cm$^{-2}$s$^{-1}$. While no hysteresis was observed in the photon index$-$flux
($\Gamma_{\gamma}$ vs F$_{\gamma}$) parameter space, there was obvious
`harder-when-brighter' behaviour observed during the large $\gamma-$ray flare.
Furthermore, during this large flare, NGC 1275 appeared to migrate from the FR
I radio galaxy to the BL Lac object region of the photon index$-$luminosity
($\Gamma_{\gamma}$ vs L$_{\gamma}$) paramater space. In this paper we present
details of our Fermi-LAT analysis of NGC 1275, including a brief discussion on
its implications for $\gamma-$ray blazar sources.
| arxiv topic:astro-ph.HE |
arxiv_dataset-23821101.2787 | New population synthesis model: Preliminary results for close double
white dwarf populations
astro-ph.SR
An update is presented to the software package SeBa for simulating single
star and binary evolution in which new stellar evolution tracks have been
implemented. SeBa is applied to study the population of close double white
dwarf and the delay time distribution of double white dwarf mergers that may
lead to Supernovae Type Ia.
| arxiv topic:astro-ph.SR |
arxiv_dataset-23831101.2887 | The Kpi vector form factor and constraints from Kl3 decays
hep-ph hep-ex
The slope and curvature parameters of the $K\pi$ vector form factor,
$F_+^{K\pi}$, are fitted to the data on $\tauKpi$ and $K_{l3}$ decays yielding
$\lambda_+'=(25.49 \pm 0.31) \times 10^{-3}$ and $\lambda_+"= (12.22 \pm 0.14)
\times 10^{-4}$. The pole position of the $K^*(892)^\pm$ is found to be at
$m_{K^*(892)^\pm}= 892.0\pm 0.5$ MeV and $\Gamma_{K^*(892)^\pm}= 46.5 \pm1.1$
MeV. The phase-space integrals relevant for $K_{l3}$ analyses and the $P$-wave
isospin-1/2 $K\pi$ phase-shift threshold parameters are also calculated.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-23841101.2987 | Support vector machines/relevance vector machine for remote sensing
classification: A review
cs.CV cs.LG
Kernel-based machine learning algorithms are based on mapping data from the
original input feature space to a kernel feature space of higher dimensionality
to solve a linear problem in that space. Over the last decade, kernel based
classification and regression approaches such as support vector machines have
widely been used in remote sensing as well as in various civil engineering
applications. In spite of their better performance with different datasets,
support vector machines still suffer from shortcomings such as
visualization/interpretation of model, choice of kernel and kernel specific
parameter as well as the regularization parameter. Relevance vector machines
are another kernel based approach being explored for classification and
regression with in last few years. The advantages of the relevance vector
machines over the support vector machines is the availability of probabilistic
predictions, using arbitrary kernel functions and not requiring setting of the
regularization parameter. This paper presents a state-of-the-art review of SVM
and RVM in remote sensing and provides some details of their use in other civil
engineering application also.
| arxiv topic:cs.CV cs.LG |
arxiv_dataset-23851101.3087 | A Note on Diffusion Limits of Chaotic Skew Product Flows
math.DS
We provide an explicit rigorous derivation of a diffusion limit - a
stochastic differential equation with additive noise - from a deterministic
skew-product flow. This flow is assumed to exhibit time-scale separation and
has the form of a slowly evolving system driven by a fast chaotic flow. Under
mild assumptions on the fast flow, we prove convergence to a stochastic
differential equation as the time-scale separation grows. In contrast to
existing work, we do not require the flow to have good mixing properties. As a
consequence, our results incorporate a large class of fast flows, including the
classical Lorenz equations.
| arxiv topic:math.DS |
arxiv_dataset-23861101.3187 | Kaon and Lambda productions in relativistic heavy ion collisions
nucl-th hep-ph
A microscopic approach has been employed to study the kaon and $\Lambda$
productions in heavy ion collisions. The productions of $K^+$ and $\Lambda$
have been studied within the framework of Boltzmann transport equation for
various beam energies. We find a non-monotonic horn like structure for
$K^+/\pi^+$ and $\Lambda/\pi$ when plotted against centre of mass energies
($\sqrt s_{\mathrm NN}$) with the assumption of initial partonic phase for
$\sqrt s_{\mathrm NN}$ beyond a certain threshold. However, the ratio
$K^+/\pi^+$ shows a monotonic nature when a hadronic initial state is
considered for all $\sqrt s_{\mathrm NN}$. Experimental values of $K^-/\pi^-$
for different $\sqrt{s_{\mathrm NN}}$ are also reproduced within the ambit of
the same formalism.
| arxiv topic:nucl-th hep-ph |
arxiv_dataset-23871101.3287 | Geometrically convergent sequences of upper and lower bounds on the
Wallis ratio and related expressions
math.CA math.NA
Sequences of algebraic upper and lower bounds on the Wallis ratio are given
with the relative errors that converge to 0 geometrically and uniformly on any
interval of the form [x_0,\infty) for x_0>-\frac12; moreover, the relative and
absolute errors converge to 0 as x\to\infty. These conclusions are based on
corresponding results for the digamma function \psi:=\Ga'/\Ga. Relations with
other relevant results are discussed, as well as the corresponding
computational aspects. This work was motivated by studies of exact bounds
involving the Student probability distribution.
| arxiv topic:math.CA math.NA |
arxiv_dataset-23881101.3387 | Collective Dynamics of Deformable Self-Propelled Particles with
Repulsive Interaction
cond-mat.soft cond-mat.stat-mech
We investigate dynamics of deformable self-propelled particles with a
repulsive interaction whose magnitude depends on the relative direction of
elongation of a pair of particles. A collective motion of the particles appears
in two dimensions. However this ordered state becomes unstable when the
particle density exceeds a certain critical threshold and the dynamics becomes
disorder. We show by a mean field analysis that this novel transition
characteristic to deformability occurs due to a saddle-node bifurcation.
| arxiv topic:cond-mat.soft cond-mat.stat-mech |
arxiv_dataset-23891101.3487 | A meaningful expansion around detailed balance
math-ph cond-mat.stat-mech math.MP
We consider Markovian dynamics modeling open mesoscopic systems which are
driven away from detailed balance by a nonconservative force. A systematic
expansion is obtained of the stationary distribution around an equilibrium
reference, in orders of the nonequilibrium forcing. The first order around
equilibrium has been known since the work of McLennan (1959), and involves the
transient irreversible entropy flux. The expansion generalizes the McLennan
formula to higher orders, complementing the entropy flux with the dynamical
activity. The latter is more kinetic than thermodynamic and is a possible
realization of Landauer's insight (1975) that, for nonequilibrium, the relative
occupation of states also depends on the noise along possible escape routes. In
that way nonlinear response around equilibrium can be meaningfully discussed in
terms of two main quantities only, the entropy flux and the dynamical activity.
The expansion makes mathematical sense as shown in the simplest cases from
exponential ergodicity.
| arxiv topic:math-ph cond-mat.stat-mech math.MP |
arxiv_dataset-23901101.3587 | Convergence Analysis of a Class of Massively Parallel Direction
Splitting Algorithms for the Navier-Stokes Equations
math.NA
We provide a convergence analysis for a new fractional time-stepping
technique for the incompressible Navier-Stokes equations based on direction
splitting. This new technique is of linear complexity, unconditionally stable
and convergent, and suitable for massive parallelization.
| arxiv topic:math.NA |
arxiv_dataset-23911101.3687 | 77Se NMR Evidence of Strongly Coupled Superconductivity in K0.8Fe2-xSe2
cond-mat.supr-con cond-mat.str-el
We report the 77Se NMR Knight shift and spin-lattice relaxation studies on
the superconducting state of the ternary iron selenide K0.8Fe2-xSe2 with Tc~30
K. Just below Tc, the Knight shift 77Kn shows an immediate drop, indicating a
singlet pairing. The spin-lattice relaxation rate 1/77T1 decreases rapidly in
the temperature range from TC to Tc/2, which can be fit with an isotropic gap
of \Delta~3.8\pm 0.5 k_BTc. The Hebel-Slichter coherence peak is not observed.
These data give bulk evidence for a strongly coupled superconductivity with
isotropic gaps in K0.8Fe2-xSe2, which is similar to other iron-based high
temperature superconductors. Below Tc/2, the spin-part of the Knight shift
levels off to a constant value (~0.09%), and the spin-lattice relaxation
follows a 1/T1 T^2 behavior, which are not well understood.
| arxiv topic:cond-mat.supr-con cond-mat.str-el |
arxiv_dataset-23921101.3787 | T(r)opical Dyson-Schwinger Equations
nucl-th hep-lat hep-ph nucl-ex
We provide a glimpse of recent progress in hadron physics made using QCD's
Dyson-Schwinger equations, reviewing: the notion of in-hadron condensates and a
putative solution of a gross problem with the cosmological constant; the
dynamical generation of quark anomalous chromo- and electro-magnetic moments,
and their material impact upon the proton's electric/magnetic form factor
ratio; a computation that simultaneously correlates the masses of meson and
baryon ground- and excited-states; and a prediction for the x->1 value of the
ratio of neutron/proton distribution functions.
| arxiv topic:nucl-th hep-lat hep-ph nucl-ex |
arxiv_dataset-23931101.3887 | Mutation-selection dynamics and error threshold in an evolutionary model
for Turing Machines
q-bio.PE
We investigate the mutation-selection dynamics for an evolutionary
computation model based on Turing Machines that we introduced in a previous
article.
The use of Turing Machines allows for very simple mechanisms of code growth
and code activation/inactivation through point mutations. To any value of the
point mutation probability corresponds a maximum amount of active code that can
be maintained by selection and the Turing machines that reach it are said to be
at the error threshold. Simulations with our model show that the Turing
machines population evolve towards the error threshold.
Mathematical descriptions of the model point out that this behaviour is due
more to the mutation-selection dynamics than to the intrinsic nature of the
Turing machines. This indicates that this result is much more general than the
model considered here and could play a role also in biological evolution.
| arxiv topic:q-bio.PE |
arxiv_dataset-23941101.3987 | Ab initio Random Structure Searching
cond-mat.mtrl-sci
It is essential to know the arrangement of the atoms in a material in order
to compute and understand its properties. Searching for stable structures of
materials using first-principles electronic structure methods, such as density
functional theory (DFT), is a rapidly growing field. Here we describe our
simple, elegant and powerful approach to searching for structures with DFT
which we call ab initio random structure searching (AIRSS). Applications to
discovering structures of solids, point defects, surfaces, and clusters are
reviewed. New results for iron clusters on graphene, silicon clusters,
polymeric nitrogen, hydrogen-rich lithium hydrides, and boron are presented.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-23951101.4087 | CP nonconservation in the leptonic sector
hep-ph hep-ex math-ph math.MP
In this paper we use an exact method to impose unitarity on moduli of
neutrino PMNS matrix recently determined, and show how one could obtain
information on CP nonconservation from a limited experimental information. One
suggests a novel type of global fit by expressing all theoretical quantities in
terms of convention independent parameters: the Jarlskog invariant $J$ and the
moduli $|U_{\alpha i}|$, able to resolve the positivity problem of $|U_{e 3}|$.
In this way the fit will directly provide a value for $J$, and if it is
different from zero it will prove the existence of CP violation in the
available experimental data. If the best fit result, $|U_{e3}|^2<0$, from M.
Maltoni {\em et al}, [New J.Phys. {\bf 6} (2004) 122] is confirmed, it will
imply a new physics in the leptonic sector.
| arxiv topic:hep-ph hep-ex math-ph math.MP |
arxiv_dataset-23961101.4187 | The Void Galaxy Survey
astro-ph.CO
The Void Galaxy Survey (VGS) is a multi-wavelength program to study $\sim$60
void galaxies. Each has been selected from the deepest interior regions of
identified voids in the SDSS redshift survey on the basis of a unique geometric
technique, with no a prior selection of intrinsic properties of the void
galaxies. The project intends to study in detail the gas content, star
formation history and stellar content, as well as kinematics and dynamics of
void galaxies and their companions in a broad sample of void environments. It
involves the HI imaging of the gas distribution in each of the VGS galaxies.
Amongst its most tantalizing findings is the possible evidence for cold gas
accretion in some of the most interesting objects, amongst which are a polar
ring galaxy and a filamentary configuration of void galaxies. Here we shortly
describe the scope of the VGS and the results of the full analysis of the pilot
sample of 15 void galaxies.
| arxiv topic:astro-ph.CO |
arxiv_dataset-23971101.4287 | The effects of the next-nearest-neighbour density-density interaction in
the atomic limit of the extended Hubbard model
cond-mat.str-el
We have studied the extended Hubbard model in the atomic limit. The
Hamiltonian analyzed consists of the effective on-site interaction U and the
intersite density-density interactions Wij (both: nearest-neighbour and
next-nearest-neighbour). The model can be considered as a simple effective
model of charge ordered insulators. The phase diagrams and thermodynamic
properties of this system have been determined within the variational approach,
which treats the on-site interaction term exactly and the intersite
interactions within the mean-field approximation. Our investigation of the
general case taking into account for the first time the effects of
longer-ranged density-density interaction (repulsive and attractive) as well as
possible phase separations shows that, depending on the values of the
interaction parameters and the electron concentration, the system can exhibit
not only several homogeneous charge ordered (CO) phases, but also various phase
separated states (CO-CO and CO-nonordered). One finds that the model considered
exhibits very interesting multicritical behaviours and features, including
among others bicritical, tricritical, critical-end and isolated critical
points.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-23981101.4387 | WIMPless dark matter and the excess gamma rays from the Galactic center
hep-ph astro-ph.HE
In this paper we discuss the excess gamma rays from the Galactic center, the
WMAP haze and the CoGeNT and DAMA results in WIMPless models. At the same time
we also investigate the low energy constraints from the anomalous magnetic
moment of leptons and from some lepton flavor violating decays. It is found
that, for scalar or vector WIMPless dark matter, neither the WMAP haze nor the
CoGeNT and DAMA observations could be explained simultaneously with the excess
gamma rays from the Galactic center. As to fermion WIMPless dark matter, it is
only marginally possible to accommodate the CoGeNT and DAMA results with the
excess gamma rays from the Galactic center with vector connector fields. On the
other hand, only scalar connector fields could interpret the WMAP haze
concerning the constraints of anomalous magnetic moment of leptons.
Furthermore, if there is only one connector field for all the charged leptons,
some lepton flavor violating decays could happen with too large branching
ratios severely violating the experimental bounds.
| arxiv topic:hep-ph astro-ph.HE |
arxiv_dataset-23991101.4487 | Emergence of one- and two-cluster states in populations of globally
pulse-coupled oscillators
nlin.AO
The subject of this paper is a system of phase-oscillators, which are
globally pulse-coupled via excitatory interaction. The appearance and stability
of one- and two-cluster-states is investigated for a family of unimodal
phase-response-curves (PRC). The PRCs and their derivatives are assumed to be
zero at the spiking point. We show that there exist stable homoclinic
connections of the one-cluster state for PRCs with the maximum located shortly
before the spiking point and coexisting stable two-clusters states when the
maximum of the PRC is located shortly after the spike.
| arxiv topic:nlin.AO |
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