Holomorphic tachyons and fractional D-branes

We study tachyon condensation on brane-antibrane systems in orbifold theories from the viewpoint of boundary string field theory. We show that the condensation of holomorphic tachyon fields generates various fractional D-branes, The boundary N = 2 supersymmetry in the worldsheet theory ensures this result exactly, Furthermore, our results are consistent with the twisted RR-charges from detailed calculations of boundary states. We also discuss the generation of RR-charges due to holomorphic tachyon fields on multiple brane-antibrane pairs in flat space, (C) 2001 Elsevier Science B,V, All rights reserved.