Primordial Non-Gaussianity in Multi-Scalar Slow-Roll Inflation

TL;DR

This paper investigates the non-Gaussianity of primordial curvature perturbations in multi-scalar slow-roll inflation models, revealing that non-separable potentials can lead to enhanced non-Gaussianity despite slow-roll suppression.

Contribution

It demonstrates that in non-separable multi-scalar inflation models, the non-Gaussianity parameter can be significantly enhanced beyond typical slow-roll suppression.

Findings

Non-separable potentials can produce large non-Gaussianity.

The non-Gaussianity parameter is a product of slow-roll suppression and exponential enhancement.

Separable potential models generally yield suppressed non-Gaussianity.

Abstract

We analyze the non-Gaussianity for primordial curvature perturbations generated in multi-scalar slow-roll inflation model including the model with non-separable potential by making use of $\delta N$ formalism. Many authors have investigated the possibility of large non-Gaussianity for the models with separable potential, and they have found that the non-linear parameter, $f_{NL}$, is suppressed by the slow-roll parameters. We show that for the non-separable models $f_{NL}$ is given by the product of a factor which is suppressed by the slow-roll parameters and a possible enhancement factor which is given by exponentials of quantities of O(1).