Cosmic strings interacting with dark strings

TL;DR

This paper explores the interaction between dark strings and cosmic strings, revealing bound states, energy-lowering mechanisms, and gravitational effects, including supermassive solutions and changing deficit angles, with implications for astrophysical observations.

Contribution

It introduces a model of dark and cosmic string interactions, demonstrating bound states, BPS bounds, and gravitational properties, advancing understanding of dark matter sector string solutions.

Findings

Dark strings and cosmic strings can form bound states.

The interaction leads to a BPS bound depending on the interaction parameter.

Dark strings can lower their energy via electromagnetic coupling.

Abstract

Motivated by astrophysical observations of excess electronic production in the galaxy, new theoretical models of the dark matter sector have been proposed in which the Standard model couples to the dark matter sector through an attractive interaction. The coupling of the Standard model to "dark strings", which are solutions of the low energy dark sector has been investigated recently. Here, we discuss the interaction between dark strings and standard cosmic strings and show that they can form bound states. In the presence of the interaction term, a Bogomolny-Prasad-Sommerfield (BPS) bound exists that depends on the interaction parameter and we observe that the attractive interaction between dark strings and cosmic strings is most efficient if the two strings are identical. Moreover, our model allows for dark string solution that can lower their energy by coupling to an electromagnetic field. We also investigate the gravitational properties of these solutions and show that they become supermassive with a singular space-time for values of the gravitational coupling larger as compared to the non-interacting case. Moreover, the deficit angle of the solutions decreases with increasing interaction.