The Inflationary Trispectrum for Models with Large Non-Gaussianities

TL;DR

This paper calculates the four-point correlation function (trispectrum) of primordial fluctuations in certain single-field inflation models, including string-inspired ones like DBI inflation, highlighting its potential observational signatures and theoretical consistency conditions.

Contribution

It provides the first detailed computation of the inflationary trispectrum for models with large non-Gaussianities, including new consistency conditions for n-point functions.

Findings

Trispectrum could be observable in future experiments.

Distinct trispectrum signatures can differentiate DBI inflation from other models.

Derived generalized consistency conditions for n-point functions.

Abstract

We compute the leading order contribution to the four-point function of the primordial curvature perturbation in a class of single field models where the inflationary Lagrangian is a general function of the inflaton and its first derivative. This class of models includes string motivated inflationary models such as DBI inflation. We find that the trispectrum for some range of parameters could potentially be observed in future experiments. Moreover, the trispectrum can distinguish DBI inflation from other inflation models with large non-Gaussianities which typically have a similar bispectrum. We also derive a set of consistency conditions for n-point functions of the primordial curvature perturbation in single field inflation, generalizing Maldacena's result for 3-point functions.