Brane gases on K3 and Calabi-Yau manifolds

We initiate the study of Brane Gas Cosmology (BGC) on manifolds with nontrivial holonomy. Such compactifications are required within the context of superstring theory in order to make connections with realistic particle physics. We study the dynamics of brane gases constructed from various string theories on background spaces having a K3 submanifold. The K3 compactifications provide a stepping stone for generalizing the model to the case of a full Calabi-Yau threefold. Duality symmetries are discussed within a cosmological context. Using a duality, we arrive at an N = 2 theory in four dimensions compactified on a Calabi-Yau manifold with SU(3) holonomy. We argue that the Brane Gas model compactified on such spaces maintains the successes of the trivial toroidal compactification while greatly enhancing its connection to particle physics. The initial state of the universe is taken to be a small, hot and dense gas of p-branes near thermal equilibrium. The universe has no initial singularity and the dynamics of string winding modes allow three spatial dimensions to grow large, providing a possible solution to the dimensionality problem of string theory.