Note on Non-Gaussianities in Two-field Inflation

TL;DR

This paper extends an analytic method to estimate non-Gaussianities in a broader class of two-field inflation models, finding that under simple assumptions, large non-Gaussianities are unlikely in the slow-roll regime.

Contribution

It generalizes an existing estimation method to a larger class of two-field inflation models and assesses their non-Gaussianity potential.

Findings

Models analyzed do not produce large non-Gaussianity in slow-roll.

The estimation method is applicable to a broader class of models.

Scanning parameter space shows no significant non-Gaussianity in the considered models.

Abstract

Two-field slow-roll inflation is the most conservative modification of a single-field model. The main motivations to study it are its entropic mode and non-Gaussianity. Several years ago, for a two-field model with additive separable potentials, Vernizzi and Wands invented an analytic method to estimate its non-Gaussianities. Later on, Choi et al. applied this method to the model with multiplicative separable potentials. In this note, we design a larger class of models whose non-Gaussianity can be estimated by the same method. Under some simplistic assumptions, roughly these models are unlikely able to generate a large non-Gaussianity. We look over some specific models of this class by scanning the full parameter space, but still no large non-Gaussianity appears in the slow-roll region. These models and scanning techniques would be useful for future model hunt if observational evidence shows up for two-field inflation.