Natural Warm Inflation

TL;DR

This paper explores a warm inflation model with axion-like fields, expanding the viable parameter space and avoiding the need for super-Planckian decay constants, unlike traditional natural inflation.

Contribution

It introduces a warm inflation framework with axion-like fields that broadens the parameter space and eliminates the requirement for Planck-scale decay constants.

Findings

Parameter space is enlarged compared to natural inflation.

The model avoids the need for axion decay constants near the Planck scale.

It provides a viable inflation scenario with sub-Planckian decay constants.

Abstract

We derive the requirements that a generic axion-like field has to satisfy in order to play the role of the inflaton field in the warm inflation scenario. Compared to the parameter space in ordinary natural inflation models, we find that the parameter space in our model is enlarged. In particular, we avoid the problem of having an axion decay constant $f$ that relates to the Planck scale, which is instead present in the ordinary natural inflation models; in fact, our model can easily accommodate values of the axion decay constant that lie well below the Planck scale.