Non-Gaussianity from the hybrid potential

TL;DR

This paper investigates non-Gaussian features in the primordial curvature perturbation generated by a hybrid inflation model with a light defect field, identifying parameter regimes consistent with observations and within reach of future experiments.

Contribution

It provides an analytic and numerical analysis of non-Gaussianity in hybrid inflation, highlighting parameter ranges that produce observable non-Gaussian signals.

Findings

Identified parameter regimes with significant non-Gaussianity

Constructed an example consistent with current power spectrum observations

Found initial conditions at horizon crossing to be natural

Abstract

We study the hybrid inflationary potential in a regime where the defect field is light, and more than 60 e-folds of accelerated expansion occur after the symmetry breaking transition. Using analytic and numerical techniques, we then identify parameter values within this regime for which the statistics of the primordial curvature perturbation are significantly non-Gaussian. Focusing on this range of parameters, we provide a specific example which leads to an observationally consistent power spectrum, and a level of non-Gaussianity within current WMAP bounds and in reach of the Planck satellite. An interesting feature of this example is that the initial conditions at horizon crossing appear quite natural.