The trispectrum in ghost inflation

TL;DR

This paper computes the trispectrum in ghost inflation, analyzing its shape and noting the absence of local form trispectrum, and discusses the limitations of existing parameters in characterizing non-local trispectra.

Contribution

It provides the first detailed calculation of the trispectrum in ghost inflation, including contact and exchange diagrams, and clarifies the shape and parameterization limitations.

Findings

Local form trispectrum is absent in ghost inflation.

Non-local trispectrum shapes lack analogous parameters to $ au_{NL}^{loc.}$ and $g_{NL}^{loc.}$.

The shape of the trispectrum is carefully characterized.

Abstract

We calculate the trispectrum in ghost inflation where both the contact diagram and scale-exchange diagram are taken into account. The shape of trispectrum is discussed carefully and we find that the local form is absent in ghost inflation. In general, for the non-local shape trispectrum there are not analogous parameters to $\tau_{NL}^{loc.}$ and $g_{NL}^{loc.}$ which can completely characterize the size of local form trispectrum.