Irruption of massive particle species during inflation

TL;DR

This paper investigates the production of massive particle species during inflation, focusing on models where their mass temporarily becomes small, leading to an irruption of particles, which could have significant cosmological implications.

Contribution

It analyzes various inflationary models that enable the irruptive production of massive particles when their mass temporarily vanishes or diminishes.

Findings

Massive particles can be produced during inflation if their mass becomes small.

Irruptive production mechanisms depend on specific inflaton coupling models.

The study identifies conditions under which particle irruption occurs.

Abstract

All species of (non-conformally-coupled) particles are produced during inflation so long as their mass $M$ is not too much larger than $H$, the expansion rate during inflation. It has been shown that if a particle species that is normally massive ($M\gg H$) couples to the inflaton field in such a way that its mass vanishes, or at least becomes small ($M < H$), for a particular value of the inflaton field, then not only are such particles produced, but an irruption of that particle species can occur during inflation. In this paper we analyze creation of a massive particle species during inflation in a variety of settings, paying particular attention to models which realize such an irruptive production mechanism.