Instantons for particles joined by strings in three dimensional gravity

TL;DR

This paper investigates instanton solutions for particle production at string endpoints in 2+1 dimensional gravity, revealing differences between Minkowski and de Sitter backgrounds and calculating related probabilities.

Contribution

It introduces a novel analysis of instantons in 3D gravity for string-particle systems, including probability computations in de Sitter space.

Findings

Minkowski space requires negative energy components for instantons.

De Sitter space allows instantons without negative energies.

Probabilities for string creation and breaking are computed.

Abstract

We study the instantons describing the production of particles at the ends of codimension-one objects (strings and struts) in $(2+1)$-dimensional Minkowski and de Sitter spaces. A Minkowskian background allows only for systems with vanishing total mass, so that either negative mass particles or negative tension struts are required. On a de Sitter background, on the other hand, we find processes describing the production of string/particle systems with no negative energies involved. We also compute the probabilities of creating and of breaking an infinite cosmic string in de Sitter space. We perform our analysis of the system in de Sitter space employing a generalization of the toroidal coordinate system to the three-sphere.