Validity of the semiclassical approximation during the preheating phase of chaotic inflation

TL;DR

This paper examines the validity of the semiclassical approximation during the preheating phase after chaotic inflation, providing a criterion to assess its applicability amidst significant backreaction effects.

Contribution

It introduces a criterion for the validity of the semiclassical approximation during preheating in chaotic inflation models.

Findings

The criterion helps determine when the semiclassical approximation remains valid.

Large backreaction effects do not necessarily invalidate the approximation if the criterion is met.

The paper addresses the applicability of semiclassical methods during the complex preheating dynamics.

Abstract

The semiclassical approximation has frequently been used to describe the initial stage of particle production, often called preheating, which occurs after the inflationary epoch in chaotic models of inflation. During this phase backreaction effects from the produced particles on the inflaton field are significant, and one might be concerned about the validity of the semiclassical approximation, even though large backreaction effects are allowed if the inflaton field is coupled to a large number of quantum fields. A criterion is presented for the validity of the semiclassical approximation in this case and the question of whether this criterion is satisfied during preheating is addressed.