Antisymmetric field in string gas cosmology

TL;DR

This paper explores how a 2-form field flux influences string gas cosmology, enabling the universe to expand into a 4-dimensional space-time by inducing a repulsive potential and overcoming previous expansion limitations.

Contribution

It demonstrates that a homogeneous 2-form field flux can induce universe expansion in string gas cosmology, allowing transition from oscillation to expansion and achieving a 4D space-time.

Findings

A 2-form field flux induces a repulsive potential facilitating expansion.

The universe transitions from oscillation to expansion with flux presence.

Tuning the 2-form field at a critical value yields a 4D expanding universe.

Abstract

We study how the introduction of a 2-form field flux modify the dynamics of a T-duality invariant string gas cosmology model of Greene, Kabat and Marnerides. It induces a repulsive potential term in the effective action for the scale factor of the spacial dimensions. Without the 2-form field flux, the universe fails to expand when the pressure due to string modes vanishes. With the presence of a homogeneous 2-form field flux, it propels 3 spacial dimensions to grow into a macroscopic 4 dimensional space-time. We find that it triggers an expansion of a universe away from the oscillating phase around the self-dual radius. We also investigate the effects of a constant 2-form field. We can obtain an expanding 4 dimensional space-time by tuning it at the critical value.