WZW branes and gerbes

TL;DR

This paper explores the role of bundle gerbes in the WZW model, analyzing their impact on symmetric branes and open string amplitudes, especially for groups covered by SU(N).

Contribution

It provides a detailed analysis of bundle gerbes on SU(N)-covered groups to determine symmetric brane spectra and relates open string amplitudes across different WZW models.

Findings

Determined the spectrum of symmetric branes using bundle gerbes.

Established a relation between open string amplitudes in different WZW models.

Clarified the role of gerbes in the boundary formulation of the WZW model.

Abstract

We reconsider the role that bundle gerbes play in the formulation of the WZW model on closed and open surfaces. In particular, we show how an analysis of bundle gerbes on groups covered by SU(N) permits to determine the spectrum of symmetric branes in the boundary version of the WZW model with such groups as the target. We also describe a simple relation between the open string amplitudes in the WZW models based on simply connected groups and in their simple-current orbifolds.