Natural inflation in Palatini $F(R)$

Abstract

$F(R)$ Palatini gravity provides a robust framework for constructing viable inflationary potentials. In this study, we examine natural inflation and show that its consistency with observational data can be restored when the model is embedded within $F(R)$ Palatini gravity, specifically for $F(R)=R+\alpha R^n$ with $7/4\lesssim n\le 2$. For completeness, we also demonstrate that models with $n>2$ do not yield comparable improvements, achieving partial agreement with the data only in the limit $n\to 2$.

Comments: 13 pages, 6 figures, refs. added, matches the published version, acknowledgments updated