Gravitational Particle Production in Loop Quantum Cosmology

TL;DR

This paper studies gravitational particle production during the bounce phase in Loop Quantum Cosmology, revealing potential limitations of current approximation methods and implications for early universe evolution.

Contribution

It provides analytical and numerical analysis of particle production in LQC, highlighting the impact of initial conditions and the validity of the dressed metric approach.

Findings

Particle production can lead to a radiation-dominated pre-inflationary phase.

Test field approximation may not be valid in certain LQC scenarios.

Extending the dressed metric approach beyond small backreaction limits affects results.

Abstract

We investigate the gravitational particle production in the bounce phase of Loop Quantum Cosmology (LQC). We perform both analytical and numerical analysis of the particle production process in a LQC scenario with Bunch-Davies vacuum initial condition in the contracting phase. We obtain that if we extend the validity of the dressed metric approach beyond the limit of small backreaction in which it is well justified, this process would lead to a radiation dominated phase in the pre-inflationary phase of LQC. Our results indicate that the test field approximation, which is required in the truncation scheme used in the dressed metric approach, might not be a valid assumption in a LQC scenario with such initial conditions.