Semiclassical decay of topological defects

TL;DR

This paper investigates the decay mechanisms of topological defects, specifically domain walls, using quantum field theory in the Hartree approximation, revealing non-perturbative channels and the role of quantum effects in their decay into particles.

Contribution

It provides a detailed quantum field theoretical analysis of defect decay, highlighting non-perturbative decay channels and the impact of quantum effects on classical structures.

Findings

Quantum effects enable decay of classical structures into particles.

Defects decay via non-perturbative channels involving classical waves.

Quantum effects clarify the decay process beyond perturbative estimates.

Abstract

Perturbative estimates suggest that extended topological defects such as cosmic strings emit few particles, but numerical simulations of the fields from which they are constructed suggest the opposite. In this paper we study the decay of the two-dimensional prototype of strings, domain walls in a simple scalar theory, solving the underlying quantum field theory in the Hartree approximation. We conclude that including the quantum effects makes the picture clear: the defects do not directly transform into particles, but there is a non-perturbative channel to microscopic classical structures in the form of propagating waves and persistent localised oscillations, which operates over a huge separation of scales. When quantum effects are included, the microscopic classical structures can decay into particles.