Hierarchical axion inflation

Phys Rev Lett. 2014 Dec 31;113(26):261301. doi: 10.1103/PhysRevLett.113.261301. Epub 2014 Dec 23.

Abstract

We propose a new field theory mechanism for generating an effective trans-Planckian decay constant from sub-Planckian ones. Using the minimal two axions and a hierarchy between two axion decay constants is sufficient for realizing inflation through nonperturbative effects only and with minimal tuning. The inflationary motion is kept entirely within a sub-Planckian domain. We outline possible strategies of embedding the model in a string theory setup.