Testing an Inflation Model with Nonminimal Derivative Coupling in the Light of PLANCK 2015 Data

TL;DR

This paper investigates a generalized inflation model with nonminimal derivative coupling, analyzing its perturbation spectrum and non-Gaussianity, and compares it with Planck 2015 data to constrain model parameters.

Contribution

It provides a comprehensive analysis of a generalized nonminimal derivative coupling inflation model, including perturbation spectra and non-Gaussianity, and demonstrates its compatibility with observational data.

Findings

Nonminimal couplings improve compatibility of chaotic inflation models with Planck data.

The model's predictions are consistent with observations at weak coupling.

Constraints on model parameters are derived from Planck 2015 data.

Abstract

We study the dynamics of a generalized inflationary model in which both the scalar field and its derivatives are coupled to the gravity. We consider a general form of the nonminimal derivative coupling in order to have a complete treatment of the model. By expanding the action up to the second order in perturbation, we study the spectrum of the primordial modes of the perturbations. Also, by expanding the action up to the third order and considering the three point correlation functions, the amplitude of the non-Gaussianity of the primordial perturbations is studied both in equilateral and orthogonal configurations. Finally, by adopting some sort of potentials, we compare the model at hand with the Planck 2015 released observational data and obtain some constraints on the model's parameters space. As an important result, we show that the nonminimal couplings help to make models of chaotic inflation, that would otherwise be in tension with Planck data, in better agreement with the data. This model is consistent with observation at weak coupling limit.