Fermion mass hierarchy in six-dimensional SO(10) grand unified theory on a T2/Z2 orbifold

We suggest a simple supersymmetric SO(01) and unified theory in 6 dimensions which produces the suitable fermion mass Hierarchies. The 5th- and 6th-dimensional coordinates are compactified on a T-2/Z(2) orbifold. The gauge and I-Eggs fields propagate in 6 dimensions while ordinal chiral matter fields are localized in 4 dimensions. The orbifolding and boundary conditions realize the gauge symmetry reduction, SU(3)(C) x SU(2)(L) x U(l)(Y) x U(1)(X), and the triplet-doublet mass splitting. We introduce extra three sets of vector-like heavy fields: two sets propagate in 6 dimensions and chiral fields which couple to them are defined as the 1st generation, and one set propagates in 5 dimensions and chiral fields which couple to them are defined as the 2nd generation. The suitable fermion mass hierarchies are generated by integrating out these vector-like heavy fields. (C) 2002 Elsevier Science B.V. All rights reserved.