Influence of interactions on particle production induced by time-varying mass terms

TL;DR

This paper explores how interactions can induce particle production in scenarios where the particle's mass remains constant, showing that interactions with time-varying fields can lead to significant particle creation.

Contribution

It introduces a formalism demonstrating particle production via interactions without direct mass variation, supported by analytic and numerical analysis.

Findings

Particle production can occur through interactions even with constant mass terms.

Interaction strength significantly influences the amount of particle production.

Produced particle densities can be comparable to direct production from mass variation.

Abstract

We have investigated effects of interaction terms on non-perturbative particle production. It is well known that time-varying masses induce abundant particle production. In this paper we have shown that it is possible to induce particle production even if the mass term of a particle species is not varying in time. Such particles are produced through the interactions with other fields, whose mass terms are varying due to a time-dependent background. The necessary formalism has been introduced and analytic and numerical calculations have been performed in a simple but illustrative model. The rather general result is that the amount of produced particles without time-dependent masses can be comparable with the particle density produced directly by the varying background if the strength of interaction terms is reasonably large.