ACT Implications for Hilltop Inflation

Abstract

We analyze in a systematic way the implications for the classes of hilltop and hilltop-squared inflation of the recent DR6 observations by the Atacama Cosmology Telescope collaboration. We find that the reported shift in the spectral index leads to parameter ranges for these models that are significantly reduced when compared to the results obtained from the {\sc Planck} observations. We mainly focus on the more dramatic implications for the hilltop-squared class, but along the way we also highlight the milder impact on the class of hilltop models.