Primordial and late-time inflation in Brans–Dicke cosmology

Abstract

The basic motivation of this work is to attempt to explain the rapidprimordial inflation and the observed slow late-time inflation by using theBrans–Dicke theory of gravity. We show that the ratio of these two inflationparameters is proportional to the square root of the Brans–Dicke parameterω . We also calculate the Hubble parameterH and the time variation of the time dependent Newtonian gravitational constantG for both regimes. The variation of the Hubble parameter predicted by Brans–Dickecosmology is shown to be consistent with recent measurements: the value ofH in the late-time future is predicted as 0.86 times the present value ofH.