Cosmologies from higher-order string corrections

TL;DR

This paper explores how higher-order string corrections can lead to nonsingular cosmological models, including Pre-Big-Bang and Ekpyrotic universes, and discusses their implications for dark energy and singularity avoidance.

Contribution

It demonstrates the construction of nonsingular bouncing solutions in string cosmology with higher-order corrections, extending previous models and analyzing their perturbations and singularity behavior.

Findings

Nonsingular solutions in Pre-Big-Bang and Ekpyrotic models

Higher-order corrections enable singularity avoidance

Potential implications for dark energy universe

Abstract

We study cosmologies based on low-energy effective string theory with higher-order string corrections to a tree-level action and with a modulus scalar field (dilaton or compactification modulus). In the presence of such corrections it is possible to construct nonsingular cosmological solutions in the context of Pre-Big-Bang and Ekpyrotic universes. We review the construction of nonsingular bouncing solutions and resulting density perturbations in Pre-Big-Bang and Ekpyrotic models. We also discuss the effect of higher-order string corrections on dark energy universe and show several interesting possibilities of the avoidance of future singularities.