D-Strings on D-Manifolds

TL;DR

This paper explores how D-strings on D-manifolds can be used to study massless solitons and enhanced gauge symmetries in type II string compactifications, providing a perturbative framework for these phenomena.

Contribution

It introduces a perturbative approach using D-strings on D-manifolds to analyze massless solitons and gauge symmetry enhancements in Calabi-Yau compactifications.

Findings

D-strings describe nearly massless solitonic states as elementary states.

The approach applies to ALE spaces with $A_n$ singularities and certain Calabi-Yau threefolds.

The spectrum includes expected massless hypermultiplets, such as in the conifold case.

Abstract

We study the mechanism for appearance of massless solitons in type II string compactifications. We find that by combining $T$-duality with strong/weak duality of type IIB in 10 dimensions enhanced gauge symmetries and massless solitonic hypermultiplets encountered in Calabi-Yau compactifications can be studied perturbatively using D-strings (the strong/weak dual to type IIB string) compactified on ``D-manifolds''. In particular the nearly massless solitonic states of the type IIB compactifications correspond to elementary states of D-strings. As examples we consider the D-string description of enhanced gauge symmetries for type IIA string compactification on ALE spaces with $A_n$ singularities and type IIB on a class of singular Calabi-Yau threefolds. The class we study includes as a special case the conifold singularity in which case the perturbative spectrum of the D-string includes the expected massless hypermultiplet with degeneracy one.