Trispectrum from Ghost Inflation

TL;DR

This paper calculates the trispectrum in ghost inflation, revealing a large non-Gaussianity parameter  and distinctive shape features that can help differentiate it from other inflation models in future observations.

Contribution

The paper provides the first detailed calculation of the trispectrum in ghost inflation, highlighting its unique shape dependence and large non-Gaussianity parameter , offering a potential observational signature.

Findings

 order of magnitude for  in ghost inflation

Distinct shape features of the trispectrum compared to DBI inflation

Potential for future experiments to distinguish ghost inflation

Abstract

Ghost inflation predicts almost scale-invariant primordial cosmological perturbations with relatively large non-Gaussianity. The bispectrum is known to have a large contribution at the wavenumbers forming an equilateral triangle and the corresponding nonlinear parameter $f_{NL}^{equil}$ is typically of order $O(10^2)$. In this paper we calculate trispectrum from ghost inflation and show that the corresponding nonlinear parameter $\tau_{NL}$ is typically of order $O(10^4)$. We investigate the shape dependence of the trispectrum and see that it has some features different from DBI inflation. Therefore, our result may be useful as a template to distinguish ghost inflation from other models of inflation by future experiments.