Inflation with non-canonical scalar fields revisited

Smaragda Lola,Emmanuel N Saridakis,Andreas Lymperis

doi:10.1140/epjc/s10052-021-09516-8

Abstract

We revisit inflation with non-canonical scalar fields by applying deformed-steepness exponential potentials. We show that the resulting scenario can lead to inflationary observables, and in particular to scalar spectral index and tensor-to-scalar ratio, in remarkable agreement with observations. Additionally, a significant advantage of the scenario is that the required parameter values, such as the non-canonicality exponent and scale, as well as the potential exponent and scale, do not need to acquire unnatural values and hence can accept a theoretical justification. Hence, we obtain a significant improvement with respect to alternative schemes, and we present distinct correlations between the model parameters that better fit the data, which can be tested in future probes. This combination of observational efficiency and theoretical justification makes the scenario at hand a good candidate for the description of inflation.

Highlights

One possible disadvantage of the above inflationary models, namely those with non-canonical terms and those with extra steepness parameter in the potential, is that the parameter values needed for acceptable observables are quite unnatural and hard to be justified from the fieldtheoretical point of view
In the simple case of canonical fields minimally coupled to gravity, and introducing the slow-roll parameters, full perturbation analysis indicates that the inflationary observables can be expressed solely in terms of the scalar potential and its derivatives [7,10,74]
We investigate the inflationary observables in the scenario of non-canonical inflation with deformedsteepness potentials

Summary

Introduction

In this work, we are interested in studying a combination of the above models, introducing a scalar field with non-canonical kinetic terms on top of a deformed-steepness potential with an extra parameter. In the simple case of canonical fields minimally coupled to gravity, and introducing the slow-roll parameters, full perturbation analysis indicates that the inflationary observables can be expressed solely in terms of the scalar potential and its derivatives [7,10,74].

Results

Conclusion