Non-Gaussian perturbations in hybrid inflation

Abstract

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