Effects of particle production during inflation

TL;DR

This paper studies how particle production during inflation causes oscillations in the primordial power spectrum, with effects depending on model parameters and linked to temporary slow-roll violations.

Contribution

It provides analytical and numerical analysis of particle production effects on the inflationary power spectrum, highlighting the origin of oscillations from slow-roll violations.

Findings

Oscillatory features appear on small scales in the power spectrum.

Oscillation amplitude depends on coupled fields, their mass, and coupling strength.

Oscillations result from a discontinuity in the inflaton's second derivative.

Abstract

The impact of particle production during inflation on the primordial curvature perturbation spectrum is investigated both analytically and numerically. We obtain an oscillatory behavior on small scales, while on large scales the spectrum is unaffected. The amplitude of the oscillations is proportional to the number of coupled fields, their mass, and the square of the coupling constant. The oscillations are due a discontinuity in the second time derivative of the inflaton, arising from a temporary violation of the slow-roll conditions. A similar effect on the power spectrum should be produced also in other inflationary models where the slow-roll conditions are temporarily violated.