D-branes and the Conifold Singularity

TL;DR

This paper investigates the behavior of higher derivative F-terms in type IIB string theory near a conifold singularity, using intersecting D-branes to understand the singularity structure and the role of massless solitons.

Contribution

It provides a detailed analysis of the singularity structure of F-terms at the conifold point using intersecting D-branes and identifies the origin of the singularity as a one-loop contribution from a massless hypermultiplet.

Findings

F_g terms exhibit expected singularity at conifold point

Massless hypermultiplet causes one-loop singularity

Open string description captures the soliton dynamics

Abstract

We analyze in detail the description of type IIB theory on a Calabi-Yau three-fold near a conifold singularity in terms of intersecting D-branes. In particular we study the singularity structure of higher derivative $F$-terms of the form $F_g W^{2g}$ where $W$ is the gravitational superfield. This singularity is expected to be due to a one -loop contribution from a charged soliton hypermultiplet becoming massless at the conifold point. In the intersecting D-brane description this soliton is described by an open string stretched between the two D-branes. After identifying the graviphoton vertex as a closed string operator we show that $F_g$'s have the expected singularity structure in the limit of vanishing soliton mass.