Generalized structures of Script N = 1 vacua

We characterize N=1 vacua of type II theories in terms of generalized complexstructure on the internal manifold M. The structure group of T(M) + T*(M) beingSU(3) x SU(3) implies the existence of two pure spinors Phi_1 and Phi_2. Theconditions for preserving N=1 supersymmetry turn out to be simplegeneralizations of equations that have appeared in the context of N=2 andtopological strings. They are (d + H wedge) Phi_1=0 and (d + H wedge) Phi_2 =F_RR. The equation for the first pure spinor implies that the internal space isa twisted generalized Calabi-Yau manifold of a hybrid complex-symplectic type,while the RR-fields serve as an integrability defect for the second.Comment: 21 pages. v2, v3: minor changes and correction