On the existence of singularity-free solutions in quartic gravity

TL;DR

This paper investigates scalar-tensor theories with quadratic Gauss-Bonnet coupling, demonstrating that under certain conditions, they admit classical solutions in flat cosmology that avoid singularities, offering potential alternatives to traditional cosmological models.

Contribution

It proves the existence of singularity-free solutions in a broad class of scalar-Gauss-Bonnet gravity models under mild assumptions.

Findings

Existence of singularity-free solutions in flat FRW backgrounds.

Conditions on the coupling function $\xi()$ that guarantee non-singular solutions.

Potential implications for early universe cosmology and alternative gravity theories.

Abstract

We study a general field theory of a scalar field coupled to gravitation through a quadratic Gauss-Bonnet term $\xi({\phi})$$R_{GB}^2$. We show that, under mild assumptions about the function $\xi(\phi)$, the classical solutions in a spatially flat FRW background include singularity - free solutions.