The Matter Bounce Curvaton Scenario

TL;DR

This paper proposes a matter bounce curvaton scenario where quantum vacuum fluctuations in a contracting universe transfer to curvature fluctuations during a non-singular bounce, potentially explaining primordial fluctuations and non-Gaussianity.

Contribution

It introduces a novel mechanism for generating scale-invariant curvature perturbations during a matter bounce, including transfer of isocurvature to adiabatic modes.

Findings

Scale-invariant spectrum of curvature fluctuations achieved

Suppression of tensor-to-scalar ratio demonstrated

New sources of non-Gaussianity identified

Abstract

Massless scalar fields originating in a quantum vacuum state acquire a scale-invariant spectrum of fluctuations in a matter-dominated contracting universe. We show that these isocurvature fluctuations transfer to a scale-invariant spectrum of curvature fluctuations during a non-singular bounce phase. This provides a mechanism for enhancing the primordial adiabatic fluctuations and suppressing the ratio of tensor to scalar perturbations. Moreover, this mechanism leads to new sources of non-Gaussianity of curvature perturbations.