Stochastic tunneling for strongly non-Gaussian inflationary theories

TL;DR

This paper analyzes stochastic tunneling in non-Gaussian inflationary theories with non-minimal kinetic terms, highlighting the conditions under which the process remains perturbative or becomes strongly coupled.

Contribution

It introduces both local and global descriptions of tunneling in non-Gaussian inflation, clarifying their consistency and the impact of sound speed deviations.

Findings

Local description aligns with Hawking-Moss tunneling results.

Tunneling becomes strongly coupled when sound speed departs from unity.

Potential for resumming strongly coupled interactions in the theory.

Abstract

We reconsider the dynamics of stochastic or thermal tunneling in theories like Dirac-Born-Infeld inflation that have non-minimal kinetic terms and, as a result, strongly non-Gaussian perturbations. We first describe a local description of the tunneling process which gives results consistent with the standard Hawking-Moss tunneling. This result is under perturbative control as long as the fluctuation determinant is well approximated by a one-loop integral. We then move to a global description, using the methodology of stochastic inflation and the in-in path integral formalism. This approach shows clearly that the tunneling process becomes strongly coupled whenever the sound speed of the tunneling trajectory departs sufficiently from unity. We argue that these two very different perspectives are nevertheless consistent, and may imply the existence of a simple resummation of the strongly coupled interactions of the field.