Exact solutions for a scalar-tensor theory through symmetries

Abstract

In this paper, we study how to determine the unknown functions for the scalar tensor model [Formula: see text] where the Ricci scalar is allowed to appear in a nonlinear way. The methods followed to determine these functions are: the matter collineation approach, the Lie group method and the Lagrangian collineation approach. We find several exact analytical solutions for a cosmological model with a FRW metric. We determine that some of the results are also valid for some anisotropic metric (e.g. the self-similar ones).