Exceptional groups from open strings

TL;DR

This paper explores how exceptional gauge groups emerge from open string configurations, including multi-pronged junctions, in type IIB string theory with 7-branes compactified on a two-sphere.

Contribution

It demonstrates that multi-pronged open string junctions naturally generate the structure of exceptional groups in a specific string theory compactification.

Findings

Exceptional groups arise from open string junctions

Multi-pronged strings generate group structure

Open string configurations reproduce gauge symmetries

Abstract

We consider type IIB theory compactified on a two-sphere in the presence of mutually nonlocal 7-branes. The BPS states associated with the gauge vectors of exceptional groups are seen to arise from open strings connecting the 7-branes, and multi-pronged open strings capable of ending on more than two 7-branes. These multi-pronged strings are built from open string junctions that arise naturally when strings cross 7-branes. The different string configurations can be multiplied as traditional open strings, and are shown to generate the structure of exceptional groups.