Brane gas-driven bulk expansion as a precursor stage to brane inflation

TL;DR

This paper presents a novel higher-dimensional string-inspired model where a hot brane gas causes initial isotropic bulk expansion, leading to slow-roll inflation of three dimensions and subsequent stabilization and reheating.

Contribution

It introduces a new mechanism for slow-roll inflation driven by brane gas dynamics in orbifolded extra dimensions, connecting bulk expansion to brane stabilization and reheating.

Findings

Bulk brane gas induces initial isotropic expansion.

Slow-roll inflation occurs as extra dimensions contract.

Radion stabilization and reheating follow from string effects.

Abstract

We propose a new way of obtaining slow-roll inflation in the context of higher dimensional models motivated by string and M theory. In our model, all extra spatial dimensions are orbifolded. The initial conditions are taken to be a hot dense bulk brane gas which drives an initial phase of isotropic bulk expansion. This phase ends when a weak potential between the orbifold fixed planes begins to dominate. For a wide class of potentials, a period during which the bulk dimensions decrease sufficiently slowly to lead to slow-roll inflation of the three dimensions parallel to the orbifold fixed planes will result. Once the separation between the orbifold fixed planes becomes of the string scale, a repulsive potential due to string effects takes over and leads to a stabilization of the radion modes. The conversion of bulk branes into radiation during the phase of bulk contraction leads to reheating.