Inflation by Alignment

TL;DR

This paper extends alignment mechanisms for pseudo-Goldstone boson inflation models, including exponential potentials from noncompact groups, leading to natural large-field inflation with potentially higher primordial tensor signals.

Contribution

It unifies various alignment mechanisms within a broader class of inflationary models, especially those with exponential potentials from noncompact groups.

Findings

Models predict larger primordial tensor signals than single-field models.

Unified framework for multiple alignment mechanisms.

Applicability to moduli in extra-dimensional theories.

Abstract

Pseudo-Goldstone bosons (pGBs) can provide technically natural inflatons, as has been comparatively well-explored in the simplest axion examples. Although inflationary success requires trans-Planckian decay constants, f > Mp, several mechanisms have been proposed to obtain this, relying on (mis-)alignments between potential and kinetic energies in multiple-field models. We extend these mechanisms to a broader class of inflationary models, including in particular the exponential potentials that arise for pGB potentials based on noncompact groups (and so which might apply to moduli in an extra-dimensional setting). The resulting potentials provide natural large-field inflationary models and can predict a larger primordial tensor signal than is true for simpler single-field versions of these models. In so doing we provide a unified treatment of several alignment mechanisms, showing how each emerges as a limit of the more general setup.