Collisions of strings with Y junctions

TL;DR

This paper investigates the dynamics of Nambu-Goto strings with junctions, providing an exact solution and analyzing intercommuting processes, revealing velocity constraints that impact cosmic string network evolution.

Contribution

It presents a simple exact solution for string junction dynamics and identifies key velocity constraints affecting string intercommutation.

Findings

Intercommuting requires relative velocities below a critical threshold.

Large velocity encounters prevent string exchange at junctions.

Implications for cosmic superstring network evolution.

Abstract

We study the dynamics of Nambu--Goto strings with junctions at which three strings meet. In particular, we exhibit one simple exact solution and examine the process of intercommuting of two straight strings, in which they exchange partners but become joined by a third string. We show that there are important kinematical constraints on this process. The exchange cannot occur if the strings meet with very large relative velocity. This may have important implications for the evolution of cosmic superstring networks and non-abelian string networks.