Bianchi V inflation in the Brans-Dicke theory?

TL;DR

This paper presents exact solutions in Brans-Dicke theory with Bianchi V metrics that exhibit inflationary expansion and evolve towards an open FRW model, highlighting inflation without a potential but noting limitations in solving horizon and flatness problems.

Contribution

It provides new exact solutions demonstrating inflation in Brans-Dicke theory without a cosmological potential, and analyzes their properties and limitations.

Findings

Inflationary solutions exist without a potential.

Solutions evolve towards an open FRW universe.

Inflation is limited by the Brans-Dicke parameter .

Abstract

It is shown some exact solutions in the Brans-Dicke (BD) theory for a Bianchi V metric having the property of inflationary expansion, graceful exit, and asymptotic evolution to a Friedmann-Robertson-Walker (FRW) open model. It is remarkable that an inflationary behaviour can occur, even without a cosmological potential or constant. However, the horizon and flatness problems cannot be solve within the standard BD theory because the inflationary period is severely restricted by the value of the BD parameter $\omega$.