Abstract: Non-trivial inflaton self-interactions can yield calculable signatures of primordial non-Gaussianity that are measurable in cosmic surveys. Surprisingly, the phase transition to slow-roll eternal inflation is often incalculable in the same models. Instead, this transition is sensitive to the non-Gaussian tail of the distribution of scalar fluctuations, which probes physics inside the horizon, potentially beyond the cutoff scale of the Effective Field Theory of Inflation. I will show how such a tail arises from non-Gaussian corrections to Stochastic Inflation. I’ll also discuss the parameter space consistent with current observations and weak coupling at horizon crossing in which the large fluctuations relevant for eternal inflation can only be determined by appealing to a UV completion.

(Based on: https://arxiv.org/abs/2111.09332)