Scalar Perturbation in Symmetric Lee-Wick Bouncing Universe

TL;DR

This paper studies scalar perturbations in a symmetric Lee-Wick bouncing universe, revealing a new initial growing mode that stabilizes post-bounce, influencing the late-time power spectrum.

Contribution

It introduces a numerical analysis of scalar perturbations in a symmetric Lee-Wick bouncing universe, highlighting a novel growing mode during contraction.

Findings

Identification of a new initial growing mode during contraction

Stabilization of the mode to a constant after bounce

Implications for the late-time power spectrum

Abstract

We investigate the scalar perturbation in the Lee-Wick bouncing universe driven by an ordinary scalar field plus a ghost field. We consider only a symmetric evolution of the universe and the scalar fields about the bouncing point. The gauge invariant Sasaki-Mukhanov variable is numerically solved in the spatially flat gauge. We find a new form of the initial perturbation growing during the contracting phase. After the bouncing, this growing mode stabilizes to a constant mode which is responsible for the late-time power spectrum.