Evaluating the Wald Entropy from two-derivative terms in quadratic actions
High Energy Physics - Theory
2015-05-28 v1 General Relativity and Quantum Cosmology
Abstract
We evaluate the Wald Noether charge entropy for a black hole in generalized theories of gravity. Expanding the Lagrangian to second order in gravitational perturbations, we show that contributions to the entropy density originate only from the coefficients of two-derivative terms. The same considerations are extended to include matter fields and to show that arbitrary powers of matter fields and their symmetrized covariant derivatives cannot contribute to the entropy density. We also explain how to use the linearized gravitational field equation rather than quadratic actions to obtain the same results. Several explicit examples are presented that allow us to clarify subtle points in the derivation and application of our method.
Cite
@article{arxiv.1106.4394,
title = {Evaluating the Wald Entropy from two-derivative terms in quadratic actions},
author = {Ram Brustein and Dan Gorbonos and Merav Hadad and A. J. M. Medved},
journal= {arXiv preprint arXiv:1106.4394},
year = {2015}
}