Galileon inflation

TL;DR

Galileon inflation is a stable higher derivative inflation model with distinctive non-Gaussian signatures, especially when the sound speed is low, making it a promising observational target.

Contribution

This paper introduces a radiatively stable Galileon inflation model protected by a covariant shift symmetry, highlighting its unique non-Gaussian features.

Findings

Non-Gaussianity can be significantly larger than standard predictions when the sound speed is small.

Galileon inflation maintains radiative stability due to symmetry protections.

The model provides distinctive observational signatures for primordial density perturbations.

Abstract

Galileon inflation is a radiatively stable higher derivative model of inflation. The model is determined by a finite number of relevant operators which are protected by a covariant generalization of the Galileon shift symmetry. We show that the nongaussianity of the primordial density perturbation generated during an epoch of Galileon inflation is a particularly powerful observational probe of these models and that, when the speed of sound is small, fNL can be larger than the usual result fNL ~ 1/c_s^2.