Non-minimally coupled Natural Inflation: Palatini and Metric formalism with the recent BICEP/Keck

TL;DR

This paper investigates how non-minimal coupling affects Natural Inflation's predictions for inflationary parameters, comparing Palatini and Metric formalisms, and aligns results with recent BICEP/Keck observations.

Contribution

It introduces the impact of non-minimal coupling on Natural Inflation within Palatini and Metric formalisms, providing updated inflationary predictions consistent with recent observational data.

Findings

Non-minimal coupling modifies inflationary parameters like $n_s$ and $r$.

Predictions are compatible with recent BICEP/Keck results.

Analysis includes both Palatini and Metric formalisms.

Abstract

In this work, we show the effect of the non-minimal coupling $\xi \phi^2 R$ on the inflationary parameters by considering the single-field inflation and present the inflationary predictions of the appealing potential for the particle physics viewpoint: Natural Inflation, an axion-like inflaton which has a cosine-type periodic potential and the inflaton naturally emerges as a pseudo-Nambu-Goldstone boson with a spontaneously broken global symmetry. We present the inflationary predictions for this potential, $n_s$, $r$, and $\alpha=\mathrm{d}n_s/\mathrm{d}\ln k$. In addition, we assume standard thermal history after inflation, and using this, for considered potential, we show compatible regions for the $n_s$, $r$ within the recent BICEP/Keck results.