A GRAND UNIFIED SUPERSYMMETRIC THEORY OF FLAVOR

A grand unified SU(5) theory is constructed with a hierarchical breaki ng of a U(2) flavor symmetry. The small parameters of the squark and s lepton mass matrices, necessary to solve the supersymmetric flavor-cha nging problem, and the intergenerational quark and lepton mass hierarc hies are both generated from the U(2) symmetry breaking parameters. Th e flavor interactions of the theory are tightly constrained, with just 10 free Peal parameters for both the fermion and scalar sectors. All but one of the 8 small fermion mass ratios, and all of the 3 small Cab ibbo-Kobayashi-Maskawa mixing angles, can be understood without introd ucing small dimensionless Yukama parameters. Predictions are made for 2 of the Cabibbo-Kobayashi-Maskawa a mixing angles and for 2 of the fe rmion masses. The six flavor mixing matrices which appeal at the neutr alino vel tices, and which in general are arbitrary unitary matrices, are determined in terms of just a single free parameter.