Thermodynamics of f (R) theories of gravity

This paper starts from a toy model for inflation in a class of modified theories of gravity in the metric formalism. Instead of the standard procedure - assuming a non-linear Lagrangian f(R) in the Jordan frame - we start from a simple phi(2) potential in the Einstein frame and investigate the corresponding f (R) in the former picture. The addition of an adhoc Cosmological Constant in the Einstein frame leads to a Thermodynamical interpretation of this physical system, which allows further insight on its (meta)stability and evolution.