The Effects of Potential Shape on Inhomogeneous Inflation

TL;DR

This paper investigates how the shape of the inflationary potential influences the robustness of single-field inflation against inhomogeneities, deriving an analytic criterion and validating it through numerical simulations.

Contribution

It introduces a simple analytic criterion for successful inflation amid inhomogeneities and demonstrates its applicability across various inflation models using numerical relativity.

Findings

Convex potentials are more robust to inhomogeneities than concave ones.

Concave potentials with super-Planckian variations are more robust than those with sub-Planckian variations.

The derived criterion accurately predicts inflation stability in numerical simulations.

Abstract

We study the robustness of single-field inflation against inhomogeneities. We derive a simple analytic criterion on the shape of the potential for successful inflation in the presence of inhomogeneities, and demonstrate its validity using full 3+1 dimensional numerical relativity simulations on several classes of popular models of single-field inflation. We find that models with convex potentials are more robust to inhomogeneities than those with concave potentials, and that concave potentials that vary on super-Planckian scales are significantly more robust than those that vary on sub-Planckian scales.