S1 - Brane Worlds and Cosmology |
Speaker_ |
Bozza, Valerio |
Talk _ |
General solution for scalar perturbations in bouncing cosmologies |
Abstract _ |
Bouncing cosmologies, suggested by String/M-theory, may provide an alternative to standard inflation to account for the origin of inhomogeneities in our universe. The fundamental question regards the correct way to evolve the scalar perturbations through the bounce. In this talk, we present the evolution of perturbations and the final spectrum for an arbitrary (spatially flat) bouncing cosmology, with the only assumption that the bounce is governed by a single physical scale. In particular, we find the condition for the pre-bounce growing mode of the Bardeen potential (which is scale-invariant in the Ekpyrotic scenario) to survive unaltered in the post-bounce. If some new physics acting at the bounce satisfies such condition, then bouncing cosmologies are entitled to become a real viable alternative to inflation for the generation of the observed inhomogeneities. References: hep-th/0502047, gr-qc/0506040, hep-th/0512066 |