Kinematic Constraints on Formation of Bound States of Cosmic Strings - Field Theoretical Approach

TL;DR

This paper tests kinematic constraints for cosmic string bound state formation using numerical simulations of the Abelian-Higgs model, confirming analytical predictions and revealing reconnection effects beyond the thin string approximation.

Contribution

It provides the first numerical validation of kinematic constraints in a field-theoretic model for cosmic string bound states, extending beyond the Nambu-Goto approximation.

Findings

Good agreement with analytical constraints

Strings can pass through each other above critical velocity

Reconnection effects influence bound state formation

Abstract

Superstring theory predicts the potential formation of string networks with bound states ending in junctions. Kinematic constraints for junction formation have been derived within the Nambu-Goto thin string approximation. Here we test these constraints numerically in the framework of the Abelian-Higgs model in the Type-I regime and report on good agreement with the analytical predictions. We also demonstrate that strings can effectively pass through each other when they meet at speeds slightly above the critical velocity permitting bound state formation. This is due to reconnection effects that are beyond the scope of the Nambu-Goto approximation.