Lattice calculation of non-Gaussianity from preheating

TL;DR

This paper demonstrates how non-Gaussian density perturbations generated during preheating can be calculated using lattice simulations, revealing constraints on inflationary models based on non-Gaussianity levels.

Contribution

It introduces a method combining lattice field theory simulations with the separate universe approximation to compute non-Gaussianity from preheating.

Findings

Some parameter values are excluded due to excessive non-Gaussianity

Preheating can produce observable non-Gaussian signals

The method assesses inflationary model viability based on non-Gaussianity

Abstract

If light scalar fields are present at the end of inflation, their non-equilibrium dynamics such as parametric resonance or a phase transition can produce non-Gaussian density perturbations. We show how these perturbations can be calculated using non-linear lattice field theory simulations and the separate universe approximation. In the massless preheating model, we find that some parameter values are excluded while others lead to acceptable but observable levels of non-Gaussianity. This shows that preheating can be an important factor in assessing the viability of inflationary models.