标题： 热力学第一定律和修改引力中FLRW宇宙的熵 显示英文标题

标题： First law of thermodynamics and entropy of FLRW universe in modified gravity

摘要： 我们研究在不同修改引力理论中以及存在完美流体物质的情况下，(非平坦) FLRW时空的观测视界相关的热力学第一定律和熵。 我们将注意力集中在那些在FLRW背景上导致二阶微分场方程的理论上。 通过这种方式，我们观察到可以仅根据观测视界的半径得到一个熵的公式。 因此，当考虑对广义相对论面积定律的修改时，可以重建与相应热力学第一定律一致的引力拉格朗日量。 显示英文摘要

摘要： We investigate the first law of thermodynamics and entropy associated to the apparent horizon of (non-flat) FLRW space-time in different theories of modified gravity and in the presence of a perfect fluid of matter. We pose our attention on those theories which lead to second order differential field equations on FLRW background. In this way, we observe that one may obtain a formula for entropy in terms of the radius of the apparent horizon only. Thus, when considering a modification to the area law of General Relativity, it is possible to reconstruct the gravitational lagrangian consistent with the corresponding first law.