Breaking Cosmic Strings without Monopoles

TL;DR

This paper demonstrates that cosmic strings can appear to end or break in universes with nontrivial topology, especially via black hole pair production, challenging the notion that they are always topologically stable.

Contribution

It introduces mechanisms for cosmic string breaking without monopoles, including configurations involving black holes and a lower bound on breaking rates via instanton calculations.

Findings

Cosmic strings can end or break in nontrivial topologies.

Black holes can serve as endpoints for cosmic strings.

A lower bound for string breaking rate via black hole pair production is provided.

Abstract

It is shown that topologically stable cosmic strings can, in fact, appear to end or to break, even in theories without monopoles. This can occur whenever the spatial topology of the universe is nontrivial. For the case of Abelian-Higgs strings, we describe the gauge and scalar field configurations necessary for a string to end on a black hole. We give a lower bound for the rate at which a cosmic string will break via black hole pair production, using an instanton calculation based on the Euclidean C-metric.