Natural Hybrid Inflation Model with Large Non-Gaussianity

TL;DR

This paper introduces a natural hybrid inflation model combining supersymmetric hybrid and natural inflation, achieving a spectral index of 0.96, sub-Planckian axion decay constant, and large non-Gaussianity while avoiding the eta-problem.

Contribution

It presents a novel inflationary model that integrates two inflation mechanisms with symmetries to address key cosmological issues and produce observable non-Gaussianity.

Findings

Spectral index of 0.96 achieved

Axion decay constant smaller than Planck scale

Large non-Gaussianity produced

Abstract

We propose an inflationary model ("natural hybrid model"), which combines the supersymmetric hybrid model and the natural inflation model to achieve the spectral index of 0.96, and the axion decay constant smaller than the Planck scale, f<< M_P. By introducing both U(1)_R and a shift symmetry and employing the minimal Kahler potential, the eta-problem can be still avoided. The two inflaton fields in this model can admit large non-Gaussianity.