By applying the island rule proposed recently, we compute the entanglement entropy of Hawking radiation and study the Page curve for the eternal black holes in massive gravity. We investigate for ...both the neutral and charged black holes which the corresponding results of Schwarzschild and Reissner–Nordström black holes are restored in the limit of massless graviton. We show for the neutral and non-extremal charged black holes that the island is not formed at the early times of the evaporation and hence the entanglement entropy increases linearly in time. However, for the extremal charged black hole, the calculation of the entanglement entropy at the early times without the island is ill-defined because the metric is divergent at the curvature singularity. This implies that new physics in the UV region must be taken into account to make the metric behaving smoothly at the very short distances. At the late times, with the emergence of one island near the event horizon, the entanglement entropy is saturated by the Bekenstein–Hawking entropy of black holes. In addition, we analyze the impact of massive gravity parameters on the size of island, the entanglement entropy, the Page time, and the scrambling time in detail.
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In this paper, we represent a resolution for the hierarchy problem where the inverse size of the extra dimension and the fundamental Planck scale would all be of the order of the TeV scale by ...proposing a fiber fabric of spacetime. The origin of the large hierarchy is essentially due to the
cosh
function which is physically originated from the dynamics of the horizontal metric in the vacuum of non-zero energy. In addition, the fiber fabric of spacetime allows us to resolve elegantly and naturally the problems of the chirality fermions and stabilizing potential for the size of the extra dimension, which are usually encountered in the higher dimensional theories. Then, we explore the inflation with the modulus of the extra dimension identified as the inflaton where our slow-roll inflationary model belongs to the E-model class with
n
=
1
. We calculate the main inflationary observables which are consistent with the present experiments. Finally, we study how the geodesic motion of neutral test particles gets modified from the extension of spacetime. We compute the radius of the photon sphere, the innermost stable circular orbit, the perihelion shift, the light bending angle, and the observables of the strong gravitational lensing and the retrolensing phenomenon. By comparing the predicted values with the experimental observations, we determine the constraints on the fiber fabric of spacetime.
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An anomaly observed recently in the
8
Be
nuclear transition by the Atomki collaboration hints at a weakly-coupled, light new gauge boson with a mass of about 17 MeV. In this paper, we propose that ...this new gauge boson comes from a short-distance structure of the spacetime, rather than from an extension of the Standard Model through adding an extra
U
(
1
)
gauge symmetry. The dominant contribution to the relevant matrix element of the
8
Be
nuclear transition is given by the axial couplings. In order to account for the
8
Be
anomaly and satisfy the current experimental constraints, the coupling constant of the new gauge boson should be about
O
(
10
-
4
-
10
-
5
)
. Our theoretical model allows understanding the origin of the smallness of the coupling constant, which is still missing or being incompletely understood in the models at which the new gauge boson has the axial couplings.
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In this paper, we have considered the heat engine and Joule–Thomson expansion for the charged AdS black hole in the context of the nonlinear electrodynamics and massive gravity. For the black hole ...heat engine, we obtained the analytical expression for the efficiency in terms of either the entropies or the temperatures and pressures in various limits. For the Joule–Thomson expansion of the black hole, we derived the isenthalpic curves in
T
-
P
diagram, the Joule–Thomson coefficient, and the inversion curves. We also indicated in detail the effects of the nonlinear electrodynamics and massive gravity on the heat engine efficiency and the Joule–Thomson expansion of the black hole.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We have derived a non-linear charged black hole solution, in the AdS spacetime, which behaves asymptotically like the RN-AdS black hole but at the short distances like a dS geometry. Thus, the black ...hole is regular. The thermodynamic quantities of the black hole are derived. Also, we analyzed in details the phase transitions of the black hole by observing the discontinuity of the heat capacity at constant pressure and the cusp type double points in the Gibbs free energy-temperature graph. Furthermore, the thermodynamic phases and their stability are investigated relying on the off-sell Gibbs free energy. Finally, we calculated the critical exponents characterizing the behavior of the relevant thermodynamic quantities near the critical point.
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In this paper, we have constructed a bottom-up holographic model for the color superconductivity (CSC) of the Yang-Mills theory with including the higher derivative corrections which allow us to ...study the CSC phase with the color number Nc ≥ 2 . First, we consider the CSC phase transition in the context of Einstein-Gauss-Bonnet (EGB) gravity. We analyze the Cooper pair condensate in the deconfinement and confinement phases which are dual to the planar GB-RN-AdS black hole and GB-AdS soliton, respectively, where the backreaction of the matter part is taken into account. By examining the breakdown of the Breitenlohner-Freedman bound in the background of the planar GB-RN-AdS black hole, we find that the positive GB coupling parameter α > 0 leads to a lower upper bound of the color number in comparison to Einstein gravity where the CSC phase for Nc ≥ 2 is not realized. But, with the α < 0 case it is possible to observe the Cooper pair condensate for Nc ≥ 2 with the reasonable magnitude of α . This is confirmed and the corresponding phase diagram is found by solving numerically the equations of motion for the gravitational system. In addition, we show that the CSC phase disappears in the confinement phase for the magnitude of α below a certain value which means that beyond that value it might lead to the breakdown region of the EGB gravity in investigating the CSC phase. However, the CSC phase transition occurring with Nc ≥ 2 requires the magnitude of the GB coupling parameter to be rather large. As a result, the GB term would no longer be considered as the correction and it also violates the boundary causality bound. We resolve this problem by including additionally the higher derivative correction for the Maxwell electrodynamics and the nonminimal coupled Maxwell field. Figure
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
From solving the equations of the motion for a system of Einstein gravity coupled to a non-linear electromagnetic field in the dS spacetime with two integral constants, we derived a static and ...spherical symmetric non-linear magnetic-charged black hole. It is indicated that this black hole solution behaves like a dS geometry in the short-distance regime. And, thus this black hole is regular. The structure of the black hole horizons is studied in detail. Also, we investigated the thermodynamics and the thermal phase transition of the black hole in both the local and global views. By observing the discontinuous change of the specific heat sign and the swallowtail structure of the free energy, we showed that the black hole can undergo a thermal phase transition between a thermodynamically unstable phase and a thermodynamically stable phase.
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New five-dimensional charged AdS black hole solutions are found in Einstein–Gauss–Bonnet gravity and the nonlinear electrodynamics. These solutions include regular black holes as well as extremal ...black holes. The first law of the black hole thermodynamics is confirmed in the extended phase space where the cosmological constant is treated as the pressure. The first and second order phase transitions are investigated by observing the behavior of the heat capacity at constant pressure and the Gibbs free energy. In addition, the equation of state for the black holes and their
P
–
V
criticality are studied. Finally, the critical exponents are found to be the same as those of the Van der Waals fluid.
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Based on the swampland program establishing the constraints that an effective field theory must satisfy in order to come from quantum gravity, we point to that if this program is true the brane-world ...scenario with the branon dark matter (DM) would be ruled out without needing the experimental observations. In other words, the constraints of quantum gravity imply that the branons must be absorbed by the Kaluza-Klein (KK) gauge bosons which are the off-diagonal components of the bulk metric to become their longitudinal modes. Interestingly, the KK gauge bosons behave as the DM and hence it leads to a geometric unification of gravity and the DM, as a natural feature of the brane-world scenario completed into quantum gravity in the ultraviolet. In addition, the KK gauge boson DM would open a particularly promising observation window to search for the DM coupling very weakly to the SM in the cosmic microwave background and the spectrum of the primordial gravitational waves.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the context of the non-linear electrodynamics and the Einstein-massive gravity, we have obtained a
4
D
non-linear charged AdS black hole solution. Then, we investigated its horizon structure. In ...addition, the thermodynamics and phase structure of this black hole solution have been studied in details. We have computed various thermodynamic quantities of the black hole, such as the temperature, entropy, the heat capacity at constant pressure, or the Gibbs free energy. The black hole can undergo the first-order, second-order phase transitions which depend crucially on the effective horizon curvature, the sign of the coupling parameter
c
1
, the characteristic parameter of the non-linear electrodynamics, as well as the pressure. Finally, we derived the equation of state and studied
P
-
V
criticality in the case of the positive effective horizon curvature.
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