Large non-Gaussianity in non-minimal inflation

TL;DR

This paper presents a two-field inflation model with a complex scalar field non-minimally coupled to gravity, demonstrating that it can generate large non-Gaussianity during slow-roll inflation, relevant for particle physics models.

Contribution

It introduces a novel two-field inflation scenario with non-minimal coupling that produces significant non-Gaussianity, linking cosmology with particle physics models.

Findings

Large non-Gaussianity can be generated during slow-roll inflation.

The model involves a complex scalar with a flat modulus and a pseudo-Goldstone angular direction.

The scenario is applicable to models like the Standard Model with two Higgs doublets.

Abstract

We consider a simple inflation model with a complex scalar field coupled to gravity non-minimally. Both the modulus and the angular directions of the complex scalar are slowly rolling, leading to two-field inflation. The modulus direction becomes flat due to the non-minimal coupling, and the angular direction becomes a pseudo-Goldstone boson from a small breaking of the global U(1) symmetry. We show that large non-Gaussianity can be produced during slow-roll inflation under a reasonable assumption on the initial condition of the angular direction. This scenario may be realized in particle physics models such as the Standard Model with two Higgs doublets.