Hybrid Natural Low Scale Inflation

TL;DR

This paper explores hybrid natural inflation models where inflation ends via a second scalar field, allowing for lower symmetry breaking scales and matching observed cosmological data.

Contribution

It introduces a hybrid natural inflation framework with a pseudo-Goldstone inflaton and demonstrates its compatibility with low inflation scales and observational constraints.

Findings

Inflation scale can be below the Planck scale in supersymmetric models.

Density perturbations and spectral index are achievable with parameter tuning.

Gravitational corrections are manageable due to low symmetry breaking scale.

Abstract

We discuss the phenomenological implications of hybrid natural inflation models in which the inflaton is a pseudo-Goldstone boson but inflation is terminated by a second scalar field. A feature of the scheme is that the scale of breaking of the Goldstone symmetry can be lower than the Planck scale and so gravitational corrections are under control. We show that, for supersymmetric models, the scale of inflation can be chosen anywhere between the Lyth upper bound and a value close to the electroweak breaking scale. Unlike previous models of low scale inflation the observed density perturbations and spectral index are readily obtained by the choice of the free parameters.