Search

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. [ABSTRACT FROM AUTHOR]

In this paper we consider the Einstein–Maxwell theory and define a combined transformation composed of diffeomorphism and U(1) gauge transformation. For generality, we assume that the generator χ of such transformation is field-dependent. We define the extended off-shell ADT current and then off-shell ADT charge such that they are conserved off-shell for the asymptotically field-dependent symmetry generator χ. Then, we define the conserved charge corresponding to the asymptotically field-dependent symmetry generator χ. We apply the presented method to find the conserved charges of the asymptotically AdS3 spacetimes in the context of the Einstein–Maxwell theory in three dimensions. Although the usual proposal for the quasi local charges provides divergent global charges for the Einstein–Maxwell theory with negative cosmological constant in three dimensions, here we avoid this problem by introducing proposed combined transformation χ [ABSTRACT FROM AUTHOR]

In the present work, a warm inflationary Universe model with viscous pressure on the brane in a high-dissipation regime is studied. We derive a condition that is required for this model to be realized in a slow-roll approximation. We also present analytic expressions for the density perturbation and the amplitude of the tensor perturbation in a longitudinal gauge. General expressions of the tensor-to-scalar ratio and the scalar spectral index and its running are obtained. We develop our model using chaotic potential. The characteristics of the model are calculated for two specific cases: (1) when the dissipative parameter Γ and the bulk viscous parameter ζ are constant parameters and (2) with the dissipative parameter as a function of scalar field ϕ and the bulk viscous parameter as a function of radiation-matter mixture energy density ρ. The parameters of the model are restricted by WMAP9 and Planck observational data. [ABSTRACT FROM AUTHOR]

We show that a BTZ black hole solution of cosmological topological massive gravity has a hidden conformal symmetry. In this regard, we consider the wave equation of a massless scalar field propagating in BTZ spacetime and find that the wave equation could be written in terms of the SL(2, R) quadratic Casimir. From the conformal coordinates, the temperatures of the dual conformal field theories (CFTs) could be read directly. Moreover, we compute the microscopic entropy of the dual CFT by the Cardy formula and find a perfect match to the Bekenstein-Hawking entropy of a BTZ black hole. Then, we consider Galilean conformal algebras (GCA), which arises as a contraction of relativistic conformal algebras (x - [?]x, t - t, [?] - 0). We show that there is a correspondence between GCA2 on the boundary and contracted BTZ in the bulk. For this purpose we obtain the central charges and temperatures of GCA2. Then, we compute the microscopic entropy of the GCA2 by the Cardy formula and find a perfect match to the Bekenstein-Hawking entropy of a BTZ black hole in a non-relativistic limit. The absorption cross section of a near-region scalar field also matches the microscopic absorption cross section of the dual GCA2. So we find further evidence that shows correspondence between a contracted BTZ black hole and two-dimensional GCA. [ABSTRACT FROM AUTHOR]

We show that the extremal Einstein-Maxwell-Dilaton-Axion (EMDA) black hole and the extremal Kaluza-Klein black hole have a hidden conformal symmetry. In this regard, we consider the wave equations of a massless scalar field propagating in EMDA and Kaluza-Klein spacetimes and find in the 'near region', the wave equations in the extremal limit can be written in terms of SL(2, R) Casimir invariants. Moreover, we obtain the microscopic entropy of the extremal EMDA black hole and extremal Kaluza-Klein black hole and find that the correlation function of a near-region scalar field matches the microscopic graybody factor of the dual 2D CFT. [ABSTRACT FROM AUTHOR]

Vacuum expectation values of the energy-momentum tensor and the Casimir forces are evaluated for scalar and electromagnetic fields in the geometry of two curved boundaries on the background of the Robertson-Walker spacetime with negative spatial curvature. The boundaries under consideration are conformal images of the flat boundaries in Rindler spacetime. Robin boundary conditions are imposed in the case of the scalar field and perfect conductor boundary conditions are assumed for the electromagnetic field. We use the conformal relation between the Robertson-Walker and Rindler spacetimes and the corresponding results for two parallel plates moving with uniform proper acceleration through the Fulling-Rindler vacuum. For the general scale factor the vacuum energy-momentum tensor is decomposed into the boundary-free and boundary-induced parts. The latter is non-diagonal. The Casimir forces are directed along the normals to the boundaries. For the Dirichlet and Neumann scalars and for the electromagnetic field these forces are attractive for all separations. [ABSTRACT FROM AUTHOR]