Non-Gaussian perturbations in hybrid inflation

Abstract

We consider second order inflationary perturbations in the case of two scalar fields, $σ$ and the inflaton $ϕ$. We derive an expression for the non-Gaussianity of perturbations and apply the results to hybrid inflation. We isolate the contributions due to $σ$ and evaluate the resulting terms to show that $σ$-induced non-Gaussianities dominate over inflaton-induced non-Gaussianities when $m^2_σ \gtrsim ηH^2$, where $η$ is the slow-roll parameter. This may provide a useful test of hybrid inflation in forthcoming CMB experiments.