Galileon intermediate inflation

TL;DR

This paper explores intermediate inflation driven by a Galileon scalar field, showing it can align with Planck 2015 observations, unlike in the standard framework, and analyzing its non-Gaussianity features.

Contribution

It introduces a Galileon-based intermediate inflation model that fits observational data and derives a unique consistency relation differing from standard inflation.

Findings

Galileon intermediate inflation fits Planck 2015 data

The model predicts non-Gaussianity close to the equilateral shape

The derived consistency relation differs from standard inflation

Abstract

We investigate intermediate inflation in the framework of a Galileon scalar field. To this aim, we first obtain the inflationary observables, including the scalar spectral index, the tensor-to-scalar ratio, the running of the scalar spectral index, as well as the non-Gaussianity parameters. Then, we examine the observational viability of the intermediate inflation within the framework of a Galileon scenario. Our results show that although the prediction of intermediate inflation in the standard framework is completely ruled out by the Planck 2015 observations, it can be put inside the allowed regions of the Planck 2015 TT,TE,EE+lowP data in the Galileon setting. Moreover, we determine the parameter space of the Galileon intermediate inflation for which the model is consistent with the Planck 2015 data. Besides, we derive the consistency relation in the Galileon scenario, and find that it differs from the standard inflation. We also estimate the running of the scalar spectral index and find that it is in well agreement with the 95\% CL constraint of the Planck 2015 results. Finally, we evaluate the local, equilateral, orthogonal, and enfolded non-Gaussianity parameters, and conclude that not only is the shape of non-Gaussianity approximately close to the equilateral one, but that it also satisfies the 68\% CL bound from the Planck 2015 data.