More on the Non-Gaussianity of Perturbations in a Non-Minimal Inflationary Model

Abstract

We study nonlinear cosmological perturbations and their possible non-Gaussian character in an extended non-minimal inflation where gravity is coupled non-minimally to both the scalar field and its derivatives. By expansion of the action up to the third order, we focus on the non-linearity and non-Gaussianity of perturbations in comparison with recent observational data. By adopting an inflation potential of the form V(phi) = (1/n)(lambda)(phi)^n, we show that for n = 4, for instance, this extended model is consistent with observation if 0.013 <lambda< 0.095 in appropriate units. By restricting the equilateral amplitude of non-Gaussianity to the observationally viable values, the coupling parameter lambda is constraint to the values lambda< 0.1.