Coupled Inflation and Brane Gases

TL;DR

This paper explores a four-dimensional effective theory derived from supergravity with brane gases, demonstrating power-law inflation solutions and a mechanism for graceful exit via brane decay, linking string cosmology to late universe models.

Contribution

It introduces a novel model coupling scalar fields and brane gases, showing inflationary solutions and a decay mechanism for ending inflation, connecting string gas cosmology with late-time cosmology.

Findings

Existence of power-law inflation solutions.

Graceful exit achieved through brane decay.

Potential connection between string gas cosmology and late universe.

Abstract

We study an effective four-dimensional theory with an action with two scalar fields minimally coupled to gravity, and with a matter action which couples to the two scalar fields via an overall field-dependent coefficient in the action. Such a theory could arise from a dimensional reduction of supergravity coupled to a gas of branes winding the compactified dimensions. We show the existence of solutions corresponding to power-law inflation. The graceful exit from inflation can be obtained by postulating the decay of the branes, as would occur if the branes are unstable in the vacuum and stabilized at high densities by plasma effects. This construction provides an avenue for connecting string gas cosmology and the late-time universe.