Construction of minimal supersymmetric Z orbifold GUT models

Taking into account modular invariance and absence of target space duality anomalies as well as chiral gauge anomalies, we found that the Z3 orbifold compactification with two Wilson lines gives a unique flipped SO(10) minimal supersymmetric grand unified model, where the hidden sector gauge group is also uniquely determined by the duality-anomaly-free condition as SU(5). We propose a dynamical mechanism of GUT symmetry breaking which may generate two hierarchical mass scales as MGUT ≈ (gst24π) Mst.