Non-Minimally Gravity-Coupled Inflationary Models

TL;DR

This paper explores non-supersymmetric inflation models with specific inflaton-curvature couplings, achieving observationally consistent spectral indices and reheating, and introduces models with large coupling constants and hilltop inflation features.

Contribution

It presents new non-minimal coupling functions in chaotic and hybrid inflation models that yield acceptable spectral indices and reheating, with detailed parameter ranges for coupling constants and energy scales.

Findings

Achieves spectral index ns=0.955 or 0.967 with tensor-to-scalar ratio r=0.2 or 0.003.

Identifies coupling constants ck in the range 0.015-0.078 for successful inflation.

Provides parameter ranges for mass m, symmetry breaking scale M, and couplings lambda, kappa.

Abstract

We consider the non-supersymmetric models of chaotic (driven by a quadratic potential) and hybrid inflation, taking into account the minimal possible radiative corrections to the inflationary potential. We show that two simple coupling functions f(sigma) (with a parameter ck involved) between the inflaton field, sigma, and the Ricci scalar curvature ensure, for sub-Planckian values of the inflaton field, observationally acceptable values for the spectral index, ns, and sufficient reheating after inflation. In the case of chaotic inflation we consider two models with large ck's resulting to ns=0.955 or 0.967 and tensor-to-scalar ratio r=0.2 or 0.003, respectively. In the case of hybrid inflation, the selected f(sigma) assists us to obtain hilltop-type inflation. For values of the relevant mass parameter, m, less than 10^6 TeV and the observationally central value of ns, we find ck=(0.015-0.078) with the relevant coupling constants lambda=kappa and the symmetry breaking scale, M, confined in the ranges (2x 10^{-7}-0.001) and (1-16.8)x10^{17} GeV, respectively.