Mirage Cosmology on Unstable D3-Brane Universe

Abstract

We study the geodesic motion of an unstable brane moving in a higher dimensional bulk spacetime. The tachyon which is coupled to a U(1) gauge field induces a non-trivial cosmological evolution. Interestingly enough, this system exhibits a much smoother initial cosmological singularity in comparison with former works.Comment: 6 pages. Talk at the RTN conference ``The Quest for Unification: Theory Confronts Experiment", Corfu, Greece, Sept, 11-18, 200