http://arxiv.org/abs/1312.2524
Space-filling S-branes can meditate a non-singular transition between a contracting and an expanding universe in the Einstein frame. Following up on previous work that uncovered such bouncing solutions in the context of weakly coupled, thermal configurations of a certain class of type II superstrings, we set up here the formalism in which we can study the evolution of metric fluctuations across such an S-brane. Our work shows that the specific nature of the S-brane which is sourced by non-trivial, massless thermal string states and appears when the universe reaches a critical, maximal temperature, allows for a scale invariant spectrum of curvature fluctuations to manifest at late times via a stringy realization of the matter bounce scenario. The non-singular transition from contraction to expansion provides calculational control over the propagation of the curvature perturbations through the bounce, furnishing a working proof of concept that such a stringy Universe can result in viable late time cosmology.
Tue, 10 Dec 13
7/67
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