D-branes and BCFT in Hpp-wave backgrounds

Abstract In this paper we study two classes of symmetric D-branes in the Nappi–Witten gravitational wave, namely D2- and S1-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.