Non-linearity analysis for cosmological inflation model with minimal and non-minimal coupling of scalar field from Horndeski theory

Abstract

In this work, we analyze the non-linearity aspect of perturbations generated in early times for cosmological inflation model with minimal and non-minimal couplings of scalar field from Horndeski theory. We study the spectral index of the perturbations and tensor-to-scalar ratio and can be seen as the evidence for inflation for some responsible coupling constant. We get the sign of non-linearity from the spectral index and tensor-to-scalar ratio for this model, and this result can be analyzed further to find non-Gaussianity.