Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Generalized second law of thermodynamics on the apparent horizon in
  modified Gauss-Bonnet gravity   Modified gravity and generalized second law (GSL) of thermodynamics are
interesting topics in the modern cosmology. In this regard, we investigate the
GSL of gravitational thermodynamics in the framework of modified Gauss-Bonnet
gravity or f(G)-gravity. We consider a spatially FRW universe filled with the
matter and radiation enclosed by the dynamical apparent horizon with the
Hawking temperature. For two viable f(G) models, we first numerically solve the
set of differential equations governing the dynamics of f(G)-gravity. Then, we
obtain the evolutions of the Hubble parameter, the Gauss-Bonnet curvature
invariant term, the density and equation of state parameters as well as the
deceleration parameter. In addition, we check the energy conditions for both
models and finally examine the validity of the GSL. For the selected f(G)
models, we conclude that both models have a stable de Sitter attractor. The
equation of state parameters behave quite similar to those of the LCDM model in
the radiation/matter dominated epochs, then they enter the phantom region
before reaching the de Sitter attractor with w=-1. The deceleration parameter
starts from the radiation/matter dominated eras, then transits from a cosmic
deceleration to acceleration and finally approaches a de Sitter regime at late
times, as expected. Furthermore, the GSL is respected for both models during
the standard radiation/matter dominated epochs. Thereafter when the universe
becomes accelerating, the GSL is violated in some ranges of scale factor. At
late times, the evolution of the GSL predicts an adiabatic behavior for the
accelerated expansion of the universe.

31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
3
The categories of this paper are: physics
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
15
The categories of this paper are: nucl-ex