Title: How robust are our constraints on Inflation?

Abstract: CMB temperature and polarization measurements from the Planck satellite and the BICEP/Keck collaboration have imposed stringent constraints on the amplitude of primordial gravitational waves (r < 0.036) and the scalar spectral index (ns = 0.9649 ± 0.0044), narrowing the range of viable inflationary models. In this talk, I will examine the extent to which these results are supported by CMB experiments other than Planck and whether recent and longstanding cosmological tensions introduce additional uncertainties surrounding these conclusions. I will argue that new physics at early times (i.e., before recombination) could have significant implications for inflation. Even mild deviations from early-time ΛCDM cosmology — potentially supported by current data — could notably alter our conclusions about which inflationary models are favored or disfavored by observations. Based on these findings, there is solid ground to conclude that constraints on inflationary parameters may be more sensitive to the cosmological model than is often realized, and that the presence of these tensions could represent a non-negligible source of uncertainty for inflation.