Wound D-branes in Gepner models

We propose a new prescription of how to represent D-branes in Gepner models in more general homology classes than those in the previous constructions. The central role is played by a certain projection acting on the Recknagel-Schomerus boundary states. Consequently, the boundary states are in most cases no longer a sum of products of N = 2 Ishibashi states, but nevertheless preserve spacetime supersymmetry and satisfy the Cardy condition. We demonstrate these in the (k = 1)(3) Gepner model in detail. and construct boundary states for D-branes wound around arbitrary rigid 1-cycles on the corresponding 2-torus. We also emphasize the necessity of some angle-dependent transformations in identifying a proper free-field realization for each brane tilted at an angle. In particular, this is essential for the Witten index to give the correct intersection numbers between the different D-branes. (C) 2001 Elsevier Science B.V. All rights reserved.