Abstract

Hybrid inflation is a two-field model where inflation ends due to an instability. In the neighborhood of the instability point, the potential is very flat and the quantum fluctuations dominate over the classical motion of the inflaton and waterfall fields. These fluctuations even determine around which minimum of the potential inflation is likely to end, so in a sense the classical trajectory itself has a quantum origin. In this talk, I will study this regime in the framework of stochastic inflation. After introducing this formalism, I will show how to numerically solve the two coupled Langevin equations controlling the evolution of the fields and present some results. I will be mostly in interested in the probability distributions of the total number of e-folds and of the inflation exit point. I will conclude with discussing the physical consequences of these results, in particular the question of how the quantum diffusion can affect the observable predictions of hybrid inflation.