Flow in Cyclic Cosmology

Abstract

In this paper, we use a known duality between expanding and contracting cosmologies to construct a dual of the inflationary flow hierarchy applicable to contracting cosmologies such as Ekpyrotic and Cyclic models. We show that the inflationary flow equations are invariant under the duality and therefore apply equally well to inflation or to cyclic cosmology. We construct a self-consistent small-parameter approximation dual to the slow-roll approximation in inflation, and calculate the power spectrum of perturbations in this limit. We also recover the matter-dominated contracting solution of Wands, and the recently proposed Adiabatic Ekpyrosis solution.

14 pages, LaTeX (V2: reference added, version submitted to PRD)

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• Horizon-preserving dualities and perturbations in non-canonical scalar field cosmologies
• On the prior dependence of constraints on the tensor-to-scalar ratio