Open string - string junction transitions

TL;DR

This paper demonstrates that geodesic string junctions are essential for describing gauge vectors in IIB superstring compactifications with 7-branes, providing explicit geometric descriptions and generalizing to non-constant dilaton and axion fields.

Contribution

It explicitly characterizes how open string geodesics and junctions represent gauge bosons in IIB superstring theory, including non-constant background fields.

Findings

Geodesic string junctions are necessary for gauge vector description.

Explicit geometric description of open string geodesics and junctions.

Generalization of mechanisms to non-constant dilaton and axion fields.

Abstract

It is confirmed that geodesic string junctions are necessary to describe the gauge vectors of symmetry groups that arise in the context of IIB superstrings compactified in the presence of nonlocal 7-branes. By examining the moduli space of 7-brane backgrounds for which the dilaton and axion fields are constant, we are able to describe explicitly and geometrically how open string geodesics can fail to be smooth, and how geodesic string junctions then become the relevant BPS representatives of the gauge bosons. The mechanisms that guarantee the existence and uniqueness of the BPS representative of any gauge vector are also shown to generalize to the case where the dilaton and axion fields are not constant.