Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Evaluating the Wald Entropy from two-derivative terms in quadratic
  actions   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.

36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
17
The categories of this paper are: q-fin
13
The categories of this paper are: quant-ph
26
The categories of this paper are: bayes-an
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
33
The categories of this paper are: plasm-ph
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
4
The categories of this paper are: cond-mat