Equilibrium description of thermodynamics in modified gravitational theories

Kazuharu Bamba, Chao Qiang Geng, Shinji Tsujikawa

Research output: Contribution to conferencePaperpeer-review

Abstract

We demonstrate that it is possible to obtain a picture of equilibrium thermodynamics on the apparent horizon in the expanding cosmological background for a wide class of modified gravity theories with the Lagrangian density f(R, φ,X), where R is the Ricci scalar and X = -(∇ φ)2/2 is the kinetic energy of a scalar field φ. In this framework, the horizon entropy S corresponding to equilibrium thermodynamics is proportional to the horizon area A with a constant coefficient, as in the Einstein gravity. We show that for a flat cosmological background with a decreasing Hubble parameter, S globally increases with time.

Original languageEnglish
Pages109-112
Number of pages4
Publication statusPublished - 2009
Externally publishedYes
Event19th Workshop on General Relativity and Gravitation in Japan, JGRG 2009 - Tokyo, Japan
Duration: 2009 Nov 302009 Dec 4

Conference

Conference19th Workshop on General Relativity and Gravitation in Japan, JGRG 2009
CountryJapan
CityTokyo
Period09/11/3009/12/4

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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