Generalised scalar-tensor theory in the Bianchi type I model

TL;DR

This paper explores solutions in a generalized scalar-tensor theory within an empty Bianchi type I cosmological model, revealing non-singular behaviors, kinetic inflation, and connections to General Relativity and string theory.

Contribution

It introduces new solutions to the scalar-tensor field equations with variable coupling, demonstrating non-singular cosmologies and inflationary behaviors.

Findings

Solutions exhibit non-singular behaviors

Presence of kinetic inflation

Some solutions connect to General Relativity and string theory

Abstract

We use a conformal transformation to find solutions to the generalised scalar-tensor theory, with a coupling constant dependent on a scalar field, in an empty Bianchi type I model. We describe the dynamical behaviour of the metric functions for three different couplings: two exact solutions to the field equations and a qualitative one are found. They exhibit non-singular behaviours and kinetic inflation. Two of them admit both General Relativity and string theory in the low-energy limit as asymptotic cases.