Consistency Relation and Non-Gaussianity in a Galileon Inflation

TL;DR

This paper investigates a Galileon inflation model, analyzing its primordial perturbations and non-Gaussianity, and tests its consistency with Planck2015 data, finding some parameter ranges compatible with observations and potential for observable non-Gaussian signals.

Contribution

The study provides a detailed analysis of non-Gaussianity and tensor spectrum tilt in Galileon inflation, including constraints from observational data and deviations from standard consistency relations.

Findings

Model consistent with Planck2015 data for certain parameters

Large non-Gaussianity possible and potentially observable in future experiments

Slight deviation from the standard inflationary consistency relation

Abstract

We study a particular Galileon inflation in the light of Planck2015 observational data in order to constraint the model parameter space. We study the spectrum of the primordial modes of the density perturbations by expanding the action up to the second order in perturbations. Then we pursue by expanding the action up to the third order and find the three point correlation functions to find the amplitude of the non-Gaussianity of the primordial perturbations in this setup. We study the amplitude of the non-Gaussianity both in equilateral and orthogonal configurations and test the model with recent observational data. Our analysis shows that for some ranges of the non-minimal coupling parameter, the model is consistent with observation and it is also possible to have large non-Gaussianity which would be observable by future improvements in experiments. Moreover, we obtain the tilt of the tensor power spectrum and test the standard inflationary consistency relation ($r=-8n_T$) against the latest bounds from the Planck2015 dataset. We find a slight deviation from the standard consistency relation in this setup. Nevertheless, such a deviation seems not to be sufficiently remarkable to be detected confidently.