Bound States of Type I D-Strings

TL;DR

This paper investigates the low-energy behavior of N type I D-strings using an O(N) gauge theory, supporting the idea that it becomes an orbifold conformal theory and matches heterotic-type I duality predictions.

Contribution

It provides evidence that the infra-red limit of the D-string gauge theory flows to an orbifold conformal theory and matches duality predictions for bound state spectra.

Findings

Elliptic genus computed for the orbifold theory.

Bound state masses and multiplicities agree with heterotic-type I duality.

Longest string sector describes D-string bound states.

Abstract

We study the infra-red limit of the O(N) gauge theory that describes the low energy modes of a system of $N$ type I D-strings and provide some support to the conjecture that, in this limit, the theory flows to an orbifold conformal theory. We compute the elliptic genus of the orbifold theory and argue that its longest string sector describes the bound states of D-strings. We show that, as a result, the masses and multiplicities of the bound states are in agreement with the predictions of heterotic-type I duality in 9 dimensions, for all the BPS charges in the lattice $\Gamma_{(1,17)}$.