On the Correspondence of Open and Closed Strings

This thesis investigates correspondences between open and closed strings. This is done on the level of coupled open-closed moduli spaces and from a string field theoretic point of view. The construction of boundary string field theory on Wess-Zumino-Witten models leads to a conjecture on closed string backgrounds appearing as non-local operators in open string field theory. Sample computations for tachyon condensation leading to curved branes support this conjecture. Additional steps are taken to study supersymmetric string theories on Calabi-Yau manifolds in the presence of bulk and boundary moduli. For the topological B-model effective bulk-induced superpotentials for D5-branes are computed to all orders in the open string couplings.