Collisions of Cosmic F- and D-strings

TL;DR

This paper investigates the outcomes of collisions between cosmic F- and D-strings using string perturbation theory, analyzing various models to understand their observational signatures and distinguishability from gauge theory solitons.

Contribution

It provides a comprehensive analysis of string collision amplitudes across different configurations and compactifications, advancing understanding of cosmic string network evolution.

Findings

Strings can be distinguished from gauge theory solitons in most cases.

Collision outcomes depend logarithmically on compactification scales.

Different string pairs exhibit varied interaction behaviors.

Abstract

Recent work suggests that fundamental and Dirichlet strings, and their (p,q) bound states, may be observed as cosmic strings. The evolution of cosmic string networks, and therefore their observational signals, depends on what happens when two strings collide. We study this in string perturbation theory for collisions between all possible pairs of strings; different cases involve sphere, disk, and annulus amplitudes. The result also depends on the details of compactification; the dependence on ratios of scales is only logarithmic, but this is still numerically important. We study a range of models and parameters, and find that in most cases these strings can be distinguished from cosmic strings that arise as gauge theory solitons.