Pure Natural Inflation Passes the ACT

Abstract: Pure natural inflation is a compelling effectively single-field model of inflation stemming from a top-down approach to the acceleration mechanism. In this short letter we show that such model is compatible with the latest CMB constraints from the Atacama Cosmology Telescope. Under both the instantaneous reheating hypothesis and standard assumptions for reheating, we rule in a non-trivial fraction of the parameter space. We apply our analysis also to a phenomenological extension of the model and chart its viable parameter space.