Mirage Cosmology on Unstable D3-Brane Universe
  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. 
Anastasios Psinas