The symmetric branes of the H4 WZW model

TL;DR

This paper reviews symmetric branes in the H4 WZW model, detailing their boundary conformal field theories, couplings, and relations to other brane configurations in AdS3 and S3, highlighting their physical and mathematical properties.

Contribution

It provides a comprehensive analysis of D2 and S1 branes in the H4 WZW model, including their couplings and connections to other brane models.

Findings

Explicit bulk-boundary couplings derived

Boundary three-point couplings characterized

Relations to AdS3 and S3 branes discussed

Abstract

We review the solution of the boundary CFTs that describe the symmetric branes in the Nappi-Witten gravitational wave, namely D2 and S1 branes. The D2 branes are the twisted branes of the model while the S1 branes are the Cardy branes. We present in both cases the bulk-boundary couplings and the boundary three-point couplings and discuss the relation with branes in AdS3 and in S3. We also discuss the analogy between the open string couplings in the H4 model and the couplings for magnetized and intersecting branes.