Oral Presentation

Non-perturbative Wavefunction of the Universe in Inflation with (Resonant) Features

Author(s): Vicharit Yingcharoenrat

Presenter: Vicharit Yingcharoenrat (Kavli IPMU, the University of Tokyo)

In this talk I will first discuss a motivation why one needs to go beyond perturbation theory (PT) in inflation as going to the tail of the distribution of the primordial fluctuations. Then I will propose that the way to go beyond PT is equivalent to performing a calculation in the semi-classical limit which captures classical non-linearities at the non-perturbative level. I will move to the application of our non-perturbative method in the resonant inflationary models, in which the inflaton potential exhibits a small oscillatory modulation. As a result, given a late-time profile of the primordial fluctuations, their probability distribution function features a non-perturbative behaviors, for example, the oscillation in the late-time field value. Finally, I will show that this result can be analytically studied using the saddle-point approximation.