Blowing-up the four-dimensional Z3 orientifold

We study the blowing-up of the four-dimensional Z3 Orientifold of Angelantonj, Bianchi, Pradisi, Sagnotti and Stanev (ABPSS) by giving nonzero vacuum expectation values (VEV's) to the twisted sector moduli blowing-up modes. The blowing-up procedure induces a Fayet-Iliopoulos (FI) term for the ''anomalous'' U(1)'s, whose magnitude depends linearly on the VEV's of the blowing-up modes. To preserve the N=1 supersymmetry, non-Abelian matter fields are forced to acquire nonzero VEV's, thus breaking (some of) the non-Abelian gauge structure and decoupling some of the matter fields. We determine the form of the FI term, construct explicit examples of non-Abelian D and F flat directions, and determine the We also determine the mass spectra, for which the restabilization reduces the number of families. surviving gauge groups of the restabilized vacua. (author)