Large trispectrum in two-field slow-roll inflation

TL;DR

This paper investigates the conditions under which two-field slow-roll inflation models can produce large local trispectra, extending existing methods to better understand non-Gaussianity evolution and its dependence on potential features.

Contribution

It simplifies and extends the heatmap approach to identify conditions for large trispectra, deriving relations between non-Gaussianity parameters and linking them to potential features.

Findings

Large trispectra can be generated under similar conditions as large bispectra.

Derived a simple relation between tauNL and fNL for separable potentials.

Showed how potential features like ridges and valleys influence non-Gaussianity parameters.

Abstract

We calculate the conditions required to produce a large local trispectrum during two-field slow-roll inflation. This is done by extending and simplifying the 'heatmap' approach developed by Byrnes et al. The conditions required to generate a large trispectrum are broadly the same as those that can produce a large bispectrum. We derive a simple relation between tauNL and fNL for models with separable potentials, and furthermore show that gNL and tauNL can be related in specific circumstances. Additionally, we interpret the heatmaps dynamically, showing how they can be used as qualitative tools to understand the evolution of non-Gaussianity during inflation. We also show how fNL, tauNL and gNL are sourced by generic shapes in the inflationary potential, namely ridges, valleys and inflection points.