Evolution of the curvature perturbations during warm inflation

TL;DR

This paper studies how curvature perturbations evolve during warm inflation, highlighting the effects of inhomogeneous diffusion rates and their potential to produce significant non-Gaussianity in the spectrum.

Contribution

It applies the delta-N formalism to warm inflation and explores the impact of inhomogeneous diffusion rates on curvature perturbations and non-Gaussianity.

Findings

Perturbations decay after horizon exit but can still influence large-scale curvature.

Inhomogeneous diffusion rates can lead to significant non-Gaussianity.

Corrections to curvature perturbations may dominate at large scales.

Abstract

This paper considers warm inflation as an interesting application of multi-field inflation. Delta-N formalism is used for the calculation of the evolution of the curvature perturbations during warm inflation. Although the perturbations considered in this paper are decaying after the horizon exit, the corrections to the curvature perturbations sourced by these perturbations can remain and dominate the curvature perturbations at large scales. In addition to the typical evolution of the curvature perturbations, inhomogeneous diffusion rate is considered for warm inflation, which may lead to significant non-Gaussianity of the spectrum.