Cosmological models in semi-classical and higher order gravitational theories

Abstract

We have studied semiclassical models with a classical scalar field, giving exact solutions in the cases of a λ φ4 and an exponential self-interaction potential, in the last case we have also studied the influence of the vacuum polarization terms on the stability of the power-law solutions. We have also found cosmological exact solutions to the higher order gravitational equations derived from a Lagrangian with a R □k R structure, and investigated the stability of the de Sitter and Minkowski space-time in the sixth order approximation of this theory.