Stable exponential cosmological solutions with zero variation of G in the Einstein-Gauss-Bonnet model with a Lambda-term

TL;DR

This paper finds stable exponential cosmological solutions in a higher-dimensional Einstein-Gauss-Bonnet model with a cosmological constant, featuring a 3D expanding space and zero variation of G, under specific fine-tuned conditions.

Contribution

It introduces a class of stable exponential solutions with zero G variation in a D-dimensional Einstein-Gauss-Bonnet model with a Lambda-term, for certain fine-tuned parameters.

Findings

Solutions exhibit exponential expansion of 3D space with zero G variation.

Stability of these solutions is proven within a class of diagonal metric cosmologies.

Specific parameter conditions (Lambda, dimensions) are identified for these solutions.

Abstract

A D-dimensional gravitational model with a Gauss-Bonnet term and the cosmological term Lambda is considered. By assuming diagonal cosmological metrics, we find, for certain fine-tuned Lambda, a class of solutions with exponential time dependence of two scale factors, governed by two Hubble-like parameters H >0 and h < 0, corresponding to factor spaces of dimensions m > 3 and l > 1, respectively, with (m,l) non-equal to (6,6), (7,4), (9,3) and D = 1 + m + l. Any of these solutions describes an exponential expansion of 3-dimensional subspace with Hubble parameter H and zero variation of the effective gravitational constant G. We prove the stability of these solutions in a class of cosmological solutions with diagonal metrics.