D-branes and BCFT in Hpp-wave backgrounds

TL;DR

This paper investigates symmetric D-branes in the Nappi-Witten gravitational wave background, explicitly solving for their structure constants, boundary couplings, and four-point functions, thus advancing understanding of open strings in curved spacetimes.

Contribution

It provides the first explicit calculations of structure constants and four-point functions for symmetric D-branes in a WZW model on a curved background.

Findings

Explicit structure constants for twisted symmetric branes in WZW models.

Boundary four-point functions for open strings in curved backgrounds.

Connections between branes in Hpp-wave, AdS3, and S^3.

Abstract

In this paper we study two classes of symmetric D-branes in the Nappi-Witten gravitational wave, namely D2 and $S 1$ branes. We solve the sewing constraints and determine the bulk-boundary couplings and the boundary three-point couplings. For the D2 brane our solution gives the first explicit results for the structure constants of the twisted symmetric branes in a WZW model. We also compute the boundary four-point functions, providing examples of open string four-point amplitudes in a curved background. We finally discuss the annulus amplitudes, the relation with branes in $AdS_3$ and in $S^3$ and the analogy between the open string couplings in the $H_4$ model and the couplings for magnetized and intersecting branes.