Rapid Tunneling and Percolation in the Landscape

TL;DR

This paper explores rapid tunneling mechanisms in the string landscape, including DBI and resonance tunneling, and discusses how multiple decay channels can lead to swift vacuum decay with cosmological implications.

Contribution

It provides a quantum field theory analysis of resonance tunneling, links DBI tunneling to resonance conditions, and discusses percolation theory's role in rapid vacuum decay.

Findings

DBI tunneling can facilitate resonance tunneling in supercritical barriers.

Multiple decay channels can cause rapid vacuum decay without tunneling enhancements.

Percolation theory suggests rapid tunneling in landscapes with many vacua.

Abstract

Motivated by the possibility of a string landscape, we reexamine tunneling of a scalar field across single/multiple barriers. Recent investigations have suggested modifications to the usual picture of false vacuum decay that lead to efficient and rapid tunneling in the landscape when certain conditions are met. This can be due to stringy effects (e.g. tunneling via the DBI action), or by effects arising due to the presence of multiple vacua (e.g. resonance tunneling). In this paper we discuss both DBI tunneling and resonance tunneling. We provide a QFT treatment of resonance tunneling using the Schr\"odinger functional approach. We also show how DBI tunneling for supercritical barriers can naturally lead to conditions suitable for resonance tunneling. We argue using basic ideas from percolation theory that tunneling can be rapid in a landscape where a typical vacuum has multiple decay channels and discuss various cosmological implications. This rapidity vacuum decay can happen even if there are no resonance/DBI tunneling enhancements, solely due to the presence of a large number of decay channels. Finally, we consider various ways of circumventing a recent no-go theorem for resonance tunneling in quantum field theory.