Comparative study of the strong backreaction regime in axion inflation: the effect of the potential

TL;DR

This study investigates how different inflationary potentials influence the dynamics of axion inflation under strong backreaction, revealing universal features and limitations of homogeneous models compared to inhomogeneous lattice simulations.

Contribution

It systematically analyzes the effect of inflationary potential choices on strong backreaction dynamics, demonstrating universality of local features and highlighting the inadequacy of homogeneous methods.

Findings

Universal local backreaction features across potentials

Inflation lengthening varies with potential choice

Homogeneous backreaction methods are insufficient in this regime

Abstract

Recent works have demonstrated the necessity of capturing the local inhomogeneous physics in axion inflation, and showed new genuine features, most notably the extension of the inflationary period dictated by an electromagnetic slow-roll phase. In this work, we further investigate the model by performing a systematic study of the effect of the inflationary potential in the dynamics during the strong backreaction regime. The results indicate that the novel features associated with the local backreaction are universal and intrinsic to the model, hence independent on the choice of inflationary potential. We find that the main quantitative differences between the different choices manifest in the lengthening of inflation. We discuss the possible observational impact of this. Finally, we assess the possible reconciliation of the homogeneous backreaction method with fully inhomogeneous lattice techniques, and obtain that the former fails to provide a correct description for the regime studied in this work.