Attractor models in scalar–tensor theories of inflation

Abstract

In this work, we study the cosmological attractor models of inflation in connection with certain scalar–tensor theories of gravity, e.g. [Formula: see text] gravity and Brans–Dicke theory. For some particular choices of the functional degrees of freedom in these theories, one obtains Starobinsky-like predictions in the ([Formula: see text]) observable plane. We have demonstrated that these choices in the Lagrangian density of certain [Formula: see text] and Brans–Dicke theories fulfil the condition of the cosmological attractors. That explains why known predictions of [Formula: see text] and Brans–Dicke theories in certain cases appear to be the predictions of the much discussed attractor theories. In addition, we did an analysis showing how the predictions of an attractor model are preserved with respect to the variation in the functional freedom of the theory.