A Natural Framework for Chaotic Inflation

TL;DR

This paper presents a natural framework for chaotic inflation using an axion-like field coupled with a 4-form, where the shift symmetry protects the axion mass and membrane emissions drive the inflationary dynamics.

Contribution

It introduces a novel model where chaotic inflation arises naturally from axion-4-form mixing, protected by shift symmetry, with a mini-landscape of flux configurations.

Findings

Inflation occurs when 4-form energy dominates.

Membrane emission reduces energy, enabling slow-roll inflation.

The model naturally reproduces chaotic inflation dynamics.

Abstract

We show that inflation with a quadratic potential occurs naturally in theories where an axion-like field mixes with a 4-form. Such an axion is massive, with the mass which arises from the mixing being protected by the axion shift symmetry. The 4-form backgrounds break this symmetry spontaneously and comprise a mini-landscape, where their fluxes can change by emission of membranes. Inflation can begin when the 4-form dominates the energy density. Eventually this energy is reduced by membrane emission and the axion can roll slowly towards its minimum, as in the simplest version of chaotic inflation.