scholarly journals Black Hole Entropy for Two Higher Derivative Theories of Gravity

Entropy ◽  
2010 ◽  
Vol 12 (10) ◽  
pp. 2186-2198 ◽  
Author(s):  
Emilio Bellini ◽  
Roberto Di Criscienzo ◽  
Lorenzo Sebastiani ◽  
Sergio Zerbini
Keyword(s):  
Black Hole ◽  
Black Hole Entropy ◽  
Higher Derivative ◽  
Theories Of Gravity

scholarly journals An exploration of the black hole entropy in Gauss–Bonnet gravity via the Weyl tensor

2021 ◽  
pp. 2150193
Author(s):  
Taha A. Malik ◽  
Rafael Lopez-Mobilia
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Weyl Tensor ◽  
Black Hole Entropy ◽  
Entropy Density ◽  
Modified Theories Of Gravity ◽  
Bonnet Gravity ◽  
Gravitational Entropy ◽  
Theories Of Gravity ◽  
Almost All

Various proposals for gravitational entropy densities have been constructed from the Weyl tensor. In almost all cases, though, these studies have been restricted to general relativity, and little has been done in modified theories of gravity. However, in this paper, we investigate the simplest proposal for an entropy density constructed from the Weyl tensor in five-dimensional Gauss–Bonnet gravity and find that it fails to reproduce the expected entropy of a black hole.

scholarly journals Horizon symmetries and hairy black holes in AdS

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Laura Donnay ◽  
Gaston Giribet ◽  
Julio Oliva
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Conformal Symmetry ◽  
Virasoro Algebra ◽  
Black Hole Entropy ◽  
Infinite Dimensional ◽  
Higher Derivative ◽  
Ads Black Holes ◽  
Local Current ◽  
3D Gravity

Abstract We investigate whether supertranslation symmetry may appear in a scenario that involves black holes in AdS space. The framework we consider is massive 3D gravity, which admits a rich black hole phase space, including stationary AdS black holes with softly decaying hair. We consider a set of asymptotic conditions that permits such decaying near the boundary, and which, in addition to the local conformal symmetry, is preserved by an extra local current. The corresponding algebra of diffeomorphisms consists of two copies of Virasoro algebra in semi-direct sum with an infinite-dimensional Abelian ideal. We then reorient the analysis to the near horizon region, where infinite-dimensional symmetries also appear. The supertranslation symmetry at the horizon yields an infinite set of non-trivial charges, which we explicitly compute. The zero-mode of these charges correctly reproduces the black hole entropy. In contrast to Einstein gravity, in the higher-derivative theory subleading terms in the near horizon expansion contribute to the near horizon charges. Such terms happen to capture the higher-curvature corrections to the Bekenstein area law.

scholarly journals An entropy current and the second law in higher derivative theories of gravity

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Sayantani Bhattacharyya ◽  
Prateksh Dhivakar ◽  
Anirban Dinda ◽  
Nilay Kundu ◽  
Milan Patra ◽  
...  
Keyword(s):  
Black Hole ◽  
Equilibrium Configuration ◽  
Second Law Of Thermodynamics ◽  
Alternative Proof ◽  
Second Law ◽  
Higher Derivative ◽  
Entropy Current ◽  
Theories Of Gravity ◽  
Dynamical Fluctuations ◽  
Set Up

Abstract We construct a proof of the second law of thermodynamics in an arbitrary diffeomorphism invariant theory of gravity working within the approximation of linearized dynamical fluctuations around stationary black holes. We achieve this by establishing the existence of an entropy current defined on the horizon of the dynamically perturbed black hole in such theories. By construction, this entropy current has non-negative divergence, suggestive of a mechanism for the dynamical black hole to approach a final equilibrium configuration via entropy production as well as the spatial flow of it on the null horizon. This enables us to argue for the second law in its strongest possible form, which has a manifest locality at each space-time point. We explicitly check that the form of the entropy current that we construct in this paper exactly matches with previously reported expressions computed considering specific four derivative theories of higher curvature gravity. Using the same set up we also provide an alternative proof of the physical process version of the first law applicable to arbitrary higher derivative theories of gravity.

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