Phases of Inflation

TL;DR

This paper explores how non-perturbative phenomena in string-inspired gauge theories with multiple axions can produce IR vacuum states suitable for inflation, potentially improving compatibility with observational data.

Contribution

It connects phases of non-Abelian gauge theories and Nambu-Jona-Lasinio interactions to different inflationary models, providing a novel string-inspired framework for inflation.

Findings

Back-reaction of infladrons flattens the axion potential.

Potential modifications can alleviate tension with CMB data.

Different gauge phases correspond to various inflationary scenarios.

Abstract

Motivated by the 4d effective field theories for closed string axions in Type II string compactifications with D-branes, we consider chiral gauge theories coupled to multiple axions. We discuss how well-known non-perturbative dynamical phenomena, such as gauge instantons, fermion confinement and Nambu-Jona-Lasinio interactions, give rise to non-trivial vacuum configurations in the IR. The fluctuations about the IR vacuum are captured by some remaining closed string axions and infladrons (scalar chiral condensate excitations), which acquire dynamical masses. By employing the full power of the effective field theory, we investigate the applicability of these IR theories as inflationary models (natural, monodromy, Starobinsky) and connect different types of inflationary scenarios to different phases of the non-Abelian gauge theory or the Nambu-Jona-Lasinio four-fermion couplings. The back-reaction of the infladrons flattens the axion potential in natural-like inflationary models, such that the tension with current CMB data with respect to the spectral index and the tensor-to-scalar ratio can be partially alleviated.