On Warm Natural Inflation and Planck 2018 Constraints

Abstract

We investigate natural inflation with non-minimal coupling to gravity, characterized either by a quadratic or a periodic term, within the warm inflation paradigm during the slow-roll stage, in both strong and weak dissipation limits; and show that, in the case of a T-linearly dependent dissipative term, it can accommodate the spectral index ns and tensor-to-scalar ratio r observables given by Planck 2018 constraints, albeit with a too-small value of the e-folding number to solve the horizon problem, providing, thus, only a partial solution to natural inflation issues, assuming a T-cubically dependent dissipative term can provide a solution to this e-folding number issue.