Inflation in Higher Dimensional Gauss-Bonnet Cosmology

TL;DR

This paper explores inflationary models in higher-dimensional Gauss-Bonnet gravity, showing that such models naturally produce inflation without an inflaton field and have diverse stable and unstable solutions.

Contribution

It demonstrates that higher-dimensional Gauss-Bonnet gravity can generate inflationary solutions without an ad hoc inflaton, revealing a rich phase space with various stable and unstable behaviors.

Findings

Rapid approach to exponential scale factors in solutions

Inflation achievable with modest hidden dimension compression

Rich structure of stable and unstable solutions

Abstract

A Gauss-Bonnet term naturally appears in the action for gravity when one considers the existence of space time with dimensions more than 1+3. A variety of inflationary models can be obtained within such a framework, once the scale factor for the hidden dimension(s) is not constrained to be the same as that of the visible ones. In particular, the need for an adhoc inflaton field is eliminated. The phase space has a rich structure with different types of solutions, both stable and unstable. For a large class of solutions, the scale factors rapidly approach an asymptotic exponential form. Furthermore, sufficient inflation can be obtained for only a modest compression of the hidden world, if the latter is of a sufficiently large dimension.