Non-perturbative Corrections to Particle Production from Coherent Oscillation

TL;DR

This paper examines particle production from coherent oscillations, highlighting the limitations of perturbative methods and introducing a time averaging approach to account for non-perturbative effects, ensuring accurate evolution of particle occupation numbers.

Contribution

It presents a novel time averaging method to incorporate non-perturbative corrections in particle production analysis from coherent oscillations.

Findings

Perturbative results fail to capture non-perturbative effects.

The time averaging method accurately models occupation number evolution.

Approximate results satisfy scaling properties from oscillation periodicity.

Abstract

We investigate particle production from coherent oscillation by using the method based on the Bogolyubov transformation. Especially, we study the case when the amplitude of the oscillation and also the coupling constants with the oscillating field are small in order to avoid the non-perturbative corrections from the broad parametric resonance. We derive the expressions for the distribution functions and the number densities of produced particles at the leading order of coupling constant. It is, however, found that these results fail to describe the exact particle production eventually due to the non-perturbative effects even if the coupling constants are small. We then introduce a simple method to handle with such corrections, i.e., the time averaging method. It is shown that this method successfully provides the evolution of the occupation numbers of the growing mode. Further, we point out that the approximate results by this method satisfy the exact scaling properties coming from the periodicity of the coherent oscillation.