In this paper, using the combined Lorenz–diffeomorphism symmetry, we find a general formula for the quasi-local conserved charge of the covariant gravity theories in a first order formalism of ...gravity. We simplify the general formula for the Lovelock theory of gravity. Afterwards, we apply the obtained formula on BHT gravity to obtain the energy and angular momentum of the rotating OTT black hole solution in the context of this theory.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Motivated by the recent work of Wang, Lin, Pavon, and Abdalla B. Wang, C.Y. Lin, D. Pavon, E. Abdalla, Phys. Lett. B 662 (2008) 1, arXiv: 0711.2214 hep-th, we generalize their work to the non-flat ...case. In particular, we provide a thermodynamical interpretation for the holographic dark energy model in a non-flat universe. For this case, the characteristic length is no more the radius of the event horizon (RE) but the event horizon radius as measured from the sphere of the horizon (L). Furthermore, when interaction between the dark components of the holographic dark energy model in the non-flat universe is present its thermodynamical interpretation changes by a stable thermal fluctuation. A relation between the interaction term of the dark components and this thermal fluctuation is obtained. In the limiting case of a flat universe, i.e. k=0, all results given in B. Wang, C.Y. Lin, D. Pavon, E. Abdalla, Phys. Lett. B 662 (2008) 1, arXiv: 0711.2214 hep-th are obtained.
In this paper we show that warped AdS3 black hole spacetime is a solution of the generalized minimal massive gravity (GMMG) and introduce suitable boundary conditions for asymptotically warped AdS3 ...spacetimes. Then we find the Killing vector fields such that transformations generated by them preserve the considered boundary conditions. We calculate the conserved charges which correspond to the obtained Killing vector fields and show that the algebra of the asymptotic conserved charges is given as the semi direct product of the Virasoro algebra with U(1) current algebra. We use a particular Sugawara construction to reconstruct the conformal algebra. Thus, we are allowed to use the Cardy formula to calculate the entropy of the warped black hole. We demonstrate that the gravitational entropy of the warped black hole exactly coincides with what we obtain via Cardy's formula. As we expect, the warped Cardy formula also gives us exactly the same result as we obtain from the usual Cardy's formula. We calculate mass and angular momentum of the warped black hole and then check that obtained mass, angular momentum and entropy to satisfy the first law of the black hole mechanics. According to the results of this paper we believe that the dual theory of the warped AdS3 black hole solution of GMMG is a warped CFT.
In this paper we obtain the flux of Hawking radiation from rotating BTZ black holes from the gauge and gravitational anomalies point of view. Then we show that the gauge and gravitational anomaly in ...BTZ spacetime is cancelled by the total flux of a 2-dimensional blackbody at the Hawking temperature of the spacetime.
A
bstract
In this paper, we consider the stability of cylindrical wormholes during evolution of universe from inflation to late time acceleration epochs. We show that there are two types of ...cylindrical wormholes. The first type is produced at the corresponding point where k black F-strings are transited to BIon configuration. This wormhole transfers energy from extra dimensions into our universe, causes inflation, loses it’s energy and vanishes. The second type of cylindrical wormhole is created by a tachyonic potential and causes a new phase of acceleration. We show that wormhole parameters grow faster than the scale factor in this era, overtake it at ripping time and lead to the destruction of universe at big rip singularity.
We calculate the transmission coefficient for a particle crossing a potential barrier in monolayer graphene with Rashba spin-orbit coupling and in bilayer graphene. We show that in both cases one can ...go from Klein tunneling regime, characterized by perfect normal transmission, to anti-Klein tunneling regime, with perfect normal reflection, by tuning the Rashba spin-orbit coupling for a monolayer or the interplane coupling for a bilayer graphene. We show that the intermediate regime is characterized by a non-monotonic behavior with oscillations and resonances in the normal transmission amplitude as a function of the coupling and of the potential parameters.
Tunneling and the Goos-Hänchen-like (GHL) shifts of quasiparticles through double rectangular potential barriers in mono-layer graphene under uniaxial strain were considered. Expressions for the ...transmission coefficient and the lateral shift of the transferred beam were obtained by considering the boundary conditions and the stationary phase method, respectively. Moreover, the numerical results of the transmission probability and the lateral shifts for three values of the merging parameter,
were presented. It was observed, for two values of
, very large shifts could be obtained and we found the demeanor of the GHL shift is adjustable by changing parameters and is influenced strongly by
. Finally, our calculations were examined by the limit condition in accordance with the results obtained for a single barrier in presence of the strong uniaxial strain.
In the present work, we study the warm tachyon inflation model in the context of "logamediate inflation," where the cosmological scale factor expands as a = a sub(0)exp (Aln t super(lambda)). The ...characteristics of this model in slow-roll approximation are presented in the following two cases: (1) The dissipative parameter Gamma is a function of the tachyon field varphi and (2)Gamma is a constant parameter. The level of non-Gaussianity of this model is found for these two cases. Scalar and tensor perturbations for this scenario are presented. The parameters appearing in our model are constrained by recent observational data (WMAP7). Harrison-Zeldovich spectrum, i.e., ns = 1, is approximately obtained for large values of lambda (i.e., lambda Asymptotically = to 50) and for normal values of the number of e-folds, i.e., N Asymptotically = to 60. On the other hand, the scale invariant spectrum (Harrison-Zeldovich spectrum) is given by using two parameters in our model. For intermediate inflation, where the cosmological scale factor expands as a = a sub(0)exp (At super(functionof)), this spectrum has been exactly obtained using one parameter, i.e., functionof = 2/3 M. R. Setare and V. Kamali, J. Cosmol. Astropart. Phys. 08 (2012) 034.
We study the four-dimensional Universe on the M2-M5 Blon in the thermal background. The Blon is a configuration in a flat space of a D-brane and a parallel anti-D-brane connected by a wormhole. When ...the branes and antibranes are well separated and the brane's spike is far from the antibrane's spike, the wormhole cannot be formed. However, when two branes are close to each other, they can be connected by a wormhole. Under this condition, there exist many channels for flowing energy from extra dimensions into our Universe. This energy dominates all other forms of energy, such as the gravitational repulsion, and brings our brief epoch of the Universe to an end in the big rip singularity. We show that at this singularity the Universe is destroyed, and one black M2-brane is formed. Finally, we test our model against WMAP, Planck, and BICEP2 data, and we obtain the ripping time. According to experimental data, the N Asymptotically = to 50 case leads to n sub(s) Asymptotically = to 0.96, where N and n sub(s) are the number e-folds and the spectral index, respectively. This standard case may be found in 0.01 < R sub(Tensor-scalar) < 0.3, where R sub(Tensor-scalar) is the tensor-to-scalar ratio. At this point, the big rip singularity occurs in a finite time t sub(rip) = 31(Gyr) for WMAP and Planck data and t sub(rip) = 28(Gyr) for BICEP2 data. By comparing this time with the time of the big rip in the brane-antibrane, we find that the wormhole in the Blonic system accelerates the destruction of the Universe.
PDF
