Designing Cyclic Universe Models

TL;DR

This paper explores the design constraints of cyclic universe models, showing they require tuning similar to inflationary models and establishing simple rules for scalar field potentials based on recent perturbation propagation studies.

Contribution

It introduces a set of design rules for cyclic models' scalar potentials, informed by recent advances in understanding perturbations during the big crunch to big bang transition.

Findings

Cyclic models require similar tuning as inflationary models.

Simple design rules for scalar potentials are established.

Perturbation propagation insights inform model constraints.

Abstract

Recent advances in understanding the propagation of perturbations through the transition from big crunch to big bang (esp. Tolley et al. hep-th/0306109) make it possible for the first time to consider the full set of phenomenological constraints on the scalar field potential in cyclic models of the universe. We show that cyclic models require a comparable degree of tuning to that needed for inflationary models. The constraints are reduced to a set of simple design rules including "fast-roll" parameters analogous to the "slow-roll" parameters in inflation.