Cerenkov radiation from collisions of straight cosmic (super)strings

TL;DR

This paper investigates how relativistic cosmic (super)strings produce Cerenkov radiation of dilatons and axions during collisions, especially emphasizing the role of ultra-relativistic velocities and string interactions.

Contribution

It introduces a detailed analysis of Cerenkov radiation from straight cosmic (super)strings moving at relativistic speeds, highlighting the impact of ultra-relativistic effects and string interactions.

Findings

Cerenkov radiation occurs during relativistic string collisions.

Radiation efficiency increases with the Lorentz factor.

Gravity dominates the interaction effects at ultra-relativistic speeds.

Abstract

We consider Cerenkov radiation which must arise when randomly oriented straight cosmic (super)strings move with relativistic velocities without intercommutation. String interactions via dilaton, two-form and gravity (gravity being the dominant force in the ultra-relativistic regime) leads to formation of superluminal sources which generate Cerenkov radiation of dilatons and axions. Though the effect is of the second order in the couplings of strings to these fields, its total efficiency is increased by high dependence of the radiation rate on the Lorentz-factor of the collision.