On Warm Natural Inflation and Planck 2018 constraints

TL;DR

This paper explores warm natural inflation models with non-minimal gravity coupling, demonstrating that certain dissipative dependencies can align with Planck 2018 constraints but face challenges with the e-folding number, offering partial solutions.

Contribution

It introduces warm natural inflation models with non-minimal coupling and analyzes how different temperature-dependent dissipation terms affect observational consistency and e-folding issues.

Findings

T-linear dissipation can match Planck 2018 spectral index and tensor-to-scalar ratio.

T-cubic dissipation can address the e-folding number problem.

Models provide partial solutions to natural inflation challenges.

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 $T$-linearly dependent dissipative term, it can accommodate the spectral index $n_s$ 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.