title: Brane gas-driven bulk expansion as a precursor stage to brane inflation.
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.
authors.affiliation: Department of Physics, McGill University, 3600 University Street, Montréal, Québec H3A 2T8, Canada.
authors.forename: Natalia
authors.initials: N
authors.lastname: Shuhmaher
authors.forename: Robert
authors.initials: R
authors.lastname: Brandenberger