Aligned Natural Inflation: Monodromies of two Axions

TL;DR

This paper explores aligned axion mechanisms in natural inflation models to address the trans-Planckian field variation problem, especially in light of recent BICEP2 observations of primordial tensor modes.

Contribution

It extends the aligned axion framework to natural inflation, providing a detailed analysis of how it can produce observable tensor modes consistent with recent data.

Findings

Aligned axions can generate sizeable tensor modes.

The mechanism addresses trans-Planckian field variation issues.

Compatibility with BICEP2 observations is demonstrated.

Abstract

Natural (axionic) inflation can accommodate sizeable primordial tensor modes but suffers from the necessity of trans-Planckian variations of the inflaton field. This problem can be solved via the mechanism of aligned axions arXiv:hep-ph/0409138, where the aligned axion spirals down in the potential of other axions. We elaborate on the mechanism in view of the recently reported observations of the BICEP2 collaboration arXiv:1403.3985.