arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 0909.2159gr-qcastro-ph.COhep-phhep-th
收藏

修正引力理论中的平衡态热力学

Equilibrium thermodynamics in modified gravitational theories

Kazuharu Bamba, Chao-Qiang Geng, Shinji Tsujikawa

摘要:

我们证明了在膨胀宇宙学背景下,对于一类具有拉格朗日密度$f(R, ϕ, X)$的修正引力理论,可以得到一幅在视视界上的平衡热力学图象,其中$R$是Ricci标量,$X$是标量场$ϕ$的动能.这来自于一个适当的定义的能量动量张量的“暗”的组成部分,尊重当地的能量守恒在约旦框架。在这个框架中,对应于平衡热力学的视界熵$S$等于视界面积$A$的四分之一,单位是引力常量$G$,就像爱因斯坦引力一样。对于一个平坦的宇宙学背景,随着哈勃参数的减小,$S$随着时间的推移而整体增加,因为它发生在可行的$f(R)$暴胀和暗能量模型中。我们还表明,在视界熵$S$的平衡描述是方便的,因为它考虑了在非平衡热力学和熵产生项的视界熵$\hat{S}$的贡献。

英文摘要:

We show 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 $X$ is the kinetic energy of a scalar field $ϕ$. This comes from a suitable definition of an energy momentum tensor of the "dark" component that respects to a local energy conservation in the Jordan frame. In this framework the horizon entropy $S$ corresponding to equilibrium thermodynamics is equal to a quarter of the horizon area $A$ in units of gravitational constant $G$, as in Einstein gravity. For a flat cosmological background with a decreasing Hubble parameter, $S$ globally increases with time, as it happens for viable $f(R)$ inflation and dark energy models. We also show that the equilibrium description in terms of the horizon entropy $S$ is convenient because it takes into account the contribution of both the horizon entropy $\hat{S}$ in non-equilibrium thermodynamics and an entropy production term.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑