Preheated inflation

TL;DR

This paper introduces a novel non-thermal particle production mechanism during inflation via narrow parametric resonance, which can produce observable signatures like oscillatory features in the primordial power spectrum and secondary gravitational waves.

Contribution

It presents a new inflationary scenario involving collective spontaneous symmetry breaking that sustains non-thermal radiation and leaves detectable imprints on cosmological observables.

Findings

Oscillatory features in the primordial power spectrum.

Resonant enhancement of the spectrum amplitude.

Secondary gravitational waves detectable by future CMB experiments.

Abstract

We propose a new mechanism of non-thermal particle production during inflation based on a narrow parametric resonance, akin to the dynamics of post-inflationary preheating. The mechanism is based on the production of scalar particles with a mass that is an oscillating function of the slowly-rolling inflaton field. This is achieved in a scenario for the collective spontaneous breaking of a U(1) gauge symmetry that, while originally proposed in the context of warm inflation, leads to non-equilibrium particle production sustaining a (sub-dominant) non-thermal radiation bath throughout inflation. We show that this may leave an observational imprint, namely oscillatory features in the primordial curvature power spectrum alongside a (mild) resonant enhancement of its amplitude, as well as secondary gravitational waves that can be probed with future CMB experiments.