Open Heterotic Strings

TL;DR

This paper classifies cosmic strings by their topological charge, proposing that in string theory, this charge determines string stability, leading to the conclusion that SO(32) heterotic strings can have endpoints, unlike E_8 x E_8 strings.

Contribution

It introduces a topological classification of cosmic strings and argues that this classification influences string stability and endpoint possibilities in heterotic string theories.

Findings

SO(32) heterotic string can have endpoints

E_8 x E_8 heterotic string cannot have endpoints

Topological charge governs string stability

Abstract

We classify potential cosmic strings according to the topological charge measurable outside the string core. We conjecture that in string theory it is this charge that governs the stability of long strings. This would imply that the SO(32) heterotic string can have endpoints, but not the E_8 x E_8 heterotic string. We give various arguments in support of this conclusion.