Stochastic Effects in Hybrid Inflation

TL;DR

This paper investigates how quantum fluctuations influence the dynamics and observable predictions of hybrid inflation by numerically analyzing stochastic effects near the instability point.

Contribution

It introduces a numerical approach to solve coupled Langevin equations in hybrid inflation, revealing the impact of quantum diffusion on inflation duration and exit point.

Findings

Quantum diffusion significantly affects the total number of e-folds.

The inflation exit point distribution is altered by stochastic effects.

Observable predictions of hybrid inflation can be modified by quantum fluctuations.

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. In this article, we study this regime in the framework of stochastic inflation. We numerically solve the two coupled Langevin equations controlling the evolution of the fields and compute the probability distributions of the total number of e-folds and of the inflation exit point. Then, we discuss the physical consequences of our results, in particular the question of how the quantum diffusion can affect the observable prediction of hybrid inflation.