Antisymmetric field in string gas cosmology

Abstract

We study how the introduction of a two-form field flux modifies the dynamics of a T-duality invariant string gas cosmology model of Greene, Kabat, and Marnerides which replaces the Newtonian-like kinetic terms in the dilaton gravity action by their relativistic counterparts. It induces a repulsive potential term in the effective action for the scale factor of the spatial dimensions. Without the two-form field flux, the Universe fails to expand when the pressure due to string modes vanishes. With the presence of a homogeneous two-form field flux, it propels three spatial dimensions to grow into a macroscopic four-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 two-form field. We can obtain an expanding four-dimensional space-time by tuning it at the critical value.