YUKAWA COUPLINGS FOR BOSONIC Z_N ORBIFOLDS: THEIR MODULI AND TWISTED SECTOR DEPENDENCE

Abstract

The three-point correlation functions with twist fields are determined for bosonic Z N orbifolds. Both the choice of the modular background (compatible with the twist) and of the (higher) twisted sectors involved are fully general. We point out a necessary restriction on the set of instantons contributing to twist field correlation functions not obtained in previous calculations. Our results show that the theory is target space duality invariant.