On Non-Gaussianities in Multi-Field Inflation (N fields): Bi- and Tri-spectra beyond Slow-Roll

TL;DR

This paper derives analytic formulas for non-Gaussian features in the primordial curvature perturbations from multi-field inflation without slow-roll assumptions, revealing conditions for observable non-Gaussianities.

Contribution

It provides the first analytic expressions for bi- and tri-spectra in multi-field inflation with a separable Hubble parameter, beyond slow-roll and separable potential assumptions.

Findings

Analytic formulas for non-linearity parameters in multi-field inflation.

Conditions under which large non-Gaussianities can be observed.

Application to an exactly solvable toy-model.

Abstract

We compute analytic expressions for the non-linearity parameters characterizing the bi- and tri-spectrum of primordial curvature perturbations generated during an inflationary epoch of the early universe driven by an arbitrary number of fields. We assume neither slow roll nor a separable potential; instead, to compute Non-Gaussianities, we assume a separable Hubble parameter. We apply the formalism to an exact solvable toy-model and show under which conditions observably large non-Gaussianities are produced.