Primordial perturbations and non-Gaussianities from modulated trapping

TL;DR

This paper introduces a novel mechanism called modulated trapping during inflation, where particle production modulates the end of inflation, generating curvature perturbations with potential observable non-Gaussianities.

Contribution

It presents a new inflationary perturbation mechanism involving modulated trapping, with detailed calculations of resulting power spectrum and non-Gaussianities, expanding understanding of primordial fluctuations.

Findings

Modulated trapping can dominate the primordial power spectrum.

The mechanism predicts potentially detectable non-Gaussianities.

The model links particle production parameters to observable cosmological signatures.

Abstract

We propose a new mechanism to generate primordial curvature perturbations, based on the resonant production of particles during inflation. It is known that this phenomenon can trap the inflaton for a fraction of e-fold. This effect is governed by the mass of the produced particles and by their coupling to the inflaton, parameters which can depend on the expectation value of other fields. If one of such additional fields - a 'modulaton' - is light, then its fluctuations, acquired during the earlier stages of inflation, will induce a spatial modulation of the trapping, and thus of the end of inflation, corresponding to a curvature perturbation. We calculate the power spectrum, bispectrum and trispectrum of the curvature perturbations generated by this mechanism, taking into account the perturbations due to the inflaton fluctuations as well. We find that modulated trapping could provide the main contribution to the observed power spectrum and lead to detectable primordial non-gaussianities.