Super-horizon perturbations and preheating

TL;DR

This paper investigates whether preheating after inflation influences large-scale curvature perturbations, concluding that in the simplest models, both linear and second-order effects are negligible, thus not affecting inflationary predictions.

Contribution

The paper provides a detailed analysis confirming that preheating does not significantly impact large-scale perturbations in simple inflationary models.

Findings

Linear perturbation effects are negligible.

Second-order effects are also negligible.

Preheating does not alter inflationary predictions in the studied model.

Abstract

It has recently been claimed by Bassett et al that preheating after inflation may affect the amplitude of curvature perturbations on large scales, undermining the usual inflationary prediction. We analyze the simplest model, and confirm the results of Jedamzik and Sigl and of Ivanov that in linear perturbation theory the effect is negligible. However the dominant effect is second-order in the field perturbation and we show that this too is negligible, and hence conclude that preheating has no significant influence on large-scale perturbations in this model. We briefly discuss the likelihood of an effect in other models.