1,441 research outputs found
Quantum gases on a torus
This manuscript is aimed at studying the thermodynamic properties of quantum
gases confined to a torus. To do that, we consider \textit{noninteracting}
gases within the grand canonical ensemble formalism. In this context, fermoins
and bosons are taken into account and the calculations are properly provided in
both analytical and numerical manners. In particular, the system turns out to
be sensitive to the topological parameter under consideration: the winding
number. Furthermore, we also derive a model in order to take into account
\textit{interacting} quantum gases. To corroborate our results, we implement
such a method for two different scenarios: a ring and a torus.Comment: 22 pages, 7 figure
Gravitational waves effects in a Lorentz-violating scenario
This paper focuses on how the production and polarization of gravitational
waves are affected by spontaneous Lorentz symmetry breaking, which is driven by
a self-interacting vector field. Specifically, we examine the impact of a
smooth quadratic potential and a non-minimal coupling, discussing the
constraints and causality features of the linearized Einstein equation. To
analyze the polarization states of a plane wave, we consider a fixed vacuum
expectation value (VEV) of the vector field. Remarkably, we verify that a
space-like background vector field modifies the polarization plane and
introduces a longitudinal degree of freedom. In order to investigate the
Lorentz violation effect on the quadrupole formula, we use the modified Green
function. Finally, we show that the space-like component of the background
field leads to a third-order time derivative of the quadrupole moment, and the
bounds for the Lorentz-breaking coefficients are estimated as well.Comment: 19 pages and 1 figur
Thermal analysis of photon-like particles in rainbow gravity
This work is devoted to study the thermodynamic behavior of photon--like
particles within the \textit{rainbow} gravity formalism. To to do this, we
chose two particular ansatzs to accomplish our calculations. First, we consider
a dispersion relation which avoids UV divergences, getting a positive effective
cosmological constant. We provide \textit{numerical} analysis for the
thermodynamic functions of the system and bounds are estimated. Furthermore, a
phase transition is also expected for this model. Second, we consider a
dispersion relation employed in the context of \textit{Gamma Ray Bursts}.
Remarkably, for this latter case, the thermodynamic properties are calculated
in an \textit{analytical} manner and they turn out to depend on the harmonic
series , gamma , polygamma and zeta Riemann
functions .Comment: 22 pages, 7 figure
Vacuum solution within a metric-affine bumblebee gravity
We consider a metric-affine extension to the gravitational sector of the
Standard-Model Extension for the Lorentz-violating coefficients and
. The general results, which are applied to a specific model called
metric-affine bumblebee gravity, are obtained. A Schwarzschild-like solution,
incorporating effects of the Lorentz symmetry breaking through coefficient
, is found. Furthermore, a complete study of the geodesics
trajectories of particles has been accomplished in this background, emphasizing
the departure from general relativity. We also compute the deflection of light
within the context of the weak field approximation and verify that there exist
two new contributions ascribed to the Lorentz symmetry breaking. As a
phenomenological application, we compare our theoretical results with
observational data in order to estimate the coefficient .Comment: 22 pages, 5 figure
Thermodynamical properties of an ideal gas in a traversable wormhole
In this work, we analyze the thermodynamic properties of non--interacting
particles under influence of the gravitational field of a traversable wormhole.
In particular, we investigate how the thermodynamic quantities are affected by
the Ellis wormhole geometry, considering three different regions to our study:
asymptotically far, close to the throat, and at the throat. The thermodynamic
quantities turn out to depend strongly on parameter that controls the wormhole
throat radius. By varying it, there exist an expressive modification in the
thermodynamic state quantities, exhibiting both usual matter and dark
energy--like behaviors. Finally, the interactions are regarded to the energy
density and it seems to indicate that it "cures" the dark energy--like
features.Comment: 29 pages and 18 figure
Gravitational traces of bumblebee gravity in metric-affine formalism
This work explores various manifestations of bumblebee gravity within the
metric--affine formalism. We investigate the impact of Lorentz violation
parameter, denoted as , on the modification of the \textit{Hawking}
temperature. Our calculations reveal that as increases, the values of the
\textit{Hawking} temperature attenuate. To examine the behavior of massless
scalar perturbations, specifically the \textit{quasinormal} modes, we employ
the WKB method. The transmission and reflection coefficients are determined
through our calculations. The outcomes indicate that a stronger
Lorentz--violating parameter results in slower damping oscillations of
gravitational waves. To comprehend the influence of the \textit{quasinormal}
spectrum on time--dependent scattering phenomena, we present a detailed
analysis of scalar perturbations in the time--domain solution. Additionally, we
conduct an investigation on shadows, revealing that larger values of
correspond to larger shadow radii. Lastly, we explore the concept of time delay
within this framework.Comment: 29 pages and 7 figure
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