Scalar fields and exact invariants in a Friedmann-Robertson-Walker spacetime

Abstract

In this work we study scalar fields in a Friedmann-Robertson-Walker space-time. We use the invariant operator formulation of Lewis and Riesenfeld in order to study the behavior of scalar fields placed in the Friedmann-Robertson-Walker space-time. In addition, we construct the coherent states in this background and establish the existence of squeezed states.