Realistic Compactification Models in Einstein-Gauss-Bonnet Gravity

TL;DR

This paper investigates the dynamical compactification of flat cosmological models in Einstein-Gauss-Bonnet gravity across various dimensions, revealing conditions for realistic compactification and constraining model parameters.

Contribution

It provides a comprehensive analysis of compactification regimes in Einstein-Gauss-Bonnet gravity for arbitrary dimensions, including vacuum and $ ext{Lambda}$-term cases, and derives parameter constraints.

Findings

Vacuum case allows Kasner compactification in all dimensions.

Exponential compactification occurs only for D ≥ 2.

In $ ext{Lambda}$-term case, only exponential compactification is possible for D ≥ 2.

Abstract

We report the results of a study on the dynamical compactification of spatially flat cosmological models in Einstein-Gauss-Bonnet gravity. The analysis was performed in the arbitrary dimension in order to be more general. We consider both vacuum and $\Lambda$-term cases. Our results suggest that for vacuum case, realistic compactification into the Kasner (power law) regime occurs with any number of dimensions ($D$), while the compactification into the exponential solution occurs only for $D \geqslant 2$. For the $\Lambda$-term case only compactification into the exponential solution exists, and it only occurs for $D \geqslant 2$ as well. Our results, combined with the bounds on Gauss-Bonnet coupling and the $\Lambda$-term ($\alpha, \Lambda$, respectively) from other considerations, allow for the tightening of the existing constraints and forbid $\alpha < 0$.