A Radiation Bounce from the Lee-Wick Construction?

TL;DR

This paper investigates whether adding radiation and its Lee-Wick partner to matter can produce a cosmological bounce, finding that it generally does not unless initial conditions are finely tuned.

Contribution

It explores the stability of Lee-Wick induced bounces in the presence of radiation and identifies the conditions needed for a bounce to occur.

Findings

Adding radiation typically prevents the bounce.

A bounce is possible only with finely tuned initial phases.

The stability of Lee-Wick bounces is sensitive to initial conditions.

Abstract

It was recently realized that matter modeled by the scalar field sector of the Lee-Wick Standard Model yields, in the context of a homogeneous and isotropic cosmological background, a bouncing cosmology. However, bouncing cosmologies induced by pressure-less matter are in general unstable to the addition of relativistic matter (i.e. radiation). Here we study the possibility of obtaining a bouncing cosmology if we add not only radiation, but also its Lee-Wick partner, to the matter sector. We find that, in general, no bounce occurs. The only way to obtain a bounce is to choose initial conditions with very special phases of the radiation field and its Lee-Wick partner.