Bispectra from two-field inflation using the long-wavelength formalism

TL;DR

This paper applies the long-wavelength formalism to compute non-Gaussianity in two-field inflation, providing exact and analytical results that enhance understanding of the origin and magnitude of non-Gaussian signals.

Contribution

It introduces an exact bispectral calculation within the long-wavelength formalism and offers explicit slow-roll expressions for various potentials, highlighting its advantages over the delta-N approach.

Findings

Derived an exact bispectral non-Gaussianity result.

Provided analytical slow-roll expressions for different potentials.

Identified a simple model with significant non-Gaussianity.

Abstract

We use the long-wavelength formalism to compute the bispectral non-Gaussianity produced in two-field inflation. We find an exact result that is used as the basis of numerical studies, and an explicit analytical slow-roll expression for several classes of potentials that gives insight into the origin and importance of the various contributions to fNL. We also discuss the momentum dependence of fNL. Based on these results we find a simple model that produces a relatively large non-Gaussianity. We show that the long-wavelength formalism is a viable alternative to the standard delta-N formalism, and can be preferable to it in certain situations.