Non-BPS States and Heterotic - Type I' Duality

TL;DR

This paper explores the duality between heterotic and Type I' string theories by analyzing non-BPS states, identifying their non-perturbative counterparts, and confirming the consistency of their stability and decay properties across the duality.

Contribution

It establishes a detailed correspondence between perturbative non-BPS states in heterotic strings and non-perturbative non-BPS D-branes in Type I' theory, including stability analysis.

Findings

Identification of heterotic non-BPS states with Type I' D-branes.

Matching of stability domains between dual theories.

Consistency of decay processes under duality.

Abstract

There are two families of non-BPS bi-spinors in the perturbative spectrum of the nine dimensional heterotic string charged under the gauge group $SO(16)\times SO(16)$. The relation between these perturbative non-BPS states and certain non-perturbative non-BPS D-brane states of the dual type I$^\prime$ theory is exhibited. The relevant branes include a $\Zop_2$ charged non-BPS D-string, and a bound state of such a D-string with a fundamental string. The domains of stability of these states as well as their decay products in both theories are determined and shown to agree with the duality map.