The failure of cosmological perturbation theory in the new ekpyrotic and cyclic ekpyrotic scenarios

Abstract

Cosmological perturbation theory fails in the new ekpyrotic and cyclic ekpyrotic scenarios, before the scale factor of the Universe reaches zero. As a result, a recently-proposed recipe for evolving the curvature perturbation through the bounce in these scenarios cannot be justified.

Comments: 10 pages. v2: Logic of the demonstration of non-linearity stated more explicitely. Remarks on non-singular bounces removed for inclusion in a later paper. v3: As accepted by Phys Lett B v4: Comment on the paper of Banks and Fischler removed following its withdrawal; more precise abstract