Large non-Gaussianity from two-component hybrid inflation

TL;DR

This paper investigates how two-field hybrid inflation models can produce large non-Gaussianities during slow-roll inflation, analyzing parameter regions and the effects of the waterfall field on observable signatures.

Contribution

It identifies conditions under which large non-Gaussianity arises in two-component hybrid inflation and examines the impact of the waterfall field on inflationary observables.

Findings

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

Loop corrections are suppressed if fields follow a classical trajectory.

Waterfall field effects can significantly alter inflationary observables.

Abstract

We study the generation of non-Gaussianity in models of hybrid inflation with two inflaton fields, (2-brid inflation). We analyse the region in the parameter and the initial condition space where a large non-Gaussianity may be generated during slow-roll inflation which is generally characterised by a large f_NL, tau_NL and a small g_NL. For certain parameter values we can satisfy tau_NL>>f_NL^2. The bispectrum is of the local type but may have a significant scale dependence. We show that the loop corrections to the power spectrum and bispectrum are suppressed during inflation, if one assume that the fields follow a classical background trajectory. We also include the effect of the waterfall field, which can lead to a significant change in the observables after the waterfall field is destabilised, depending on the couplings between the waterfall and inflaton fields.