Study of a Class of Four Dimensional Nonsingular Cosmological Bounces

TL;DR

This paper investigates a new class of four-dimensional nonsingular, time-symmetric cosmological bounces driven by negative energy density fluids, analyzing metric perturbations and conditions for scale-invariant spectra.

Contribution

It introduces a novel model of nonsingular bounces with analytic solutions for perturbations and discusses conditions for scale invariance in the spectra.

Findings

Analytic solutions for metric perturbations across the bounce

Conditions identified for generating scale-invariant spectra

Demonstration of a nonsingular, time-symmetric bounce model

Abstract

We study a novel class of nonsingular time-symmetric cosmological bounces. In this class of four dimensional models the bounce is induced by a perfect fluid with a negative energy density. Metric perturbations are solved in an analytic way all through the bounce. The conditions for generating a scale invariant spectrum of tensor and scalar metric perturbations are discussed.