A new approach to Yukawa textures in supersymmetric unified models with gauged family symmetries

The origin of texture zeroes in the Yukawa matrices may be accounted for by appealing to a broken gauged family symmetry such as U(1)X, where such symmetries arise naturally from string theories. In order to improve the predictive power of such models we appeal to quark-lepton unification where additional Clebsch texture zeroes appear, leading to an entirely new class of models. We illustrate these ideas in the context of the Pati-Salam gauge group SU(4) solar mass SU(2)L solar mass SU(2)R supplemented by a U(1)X gauged family symmetry. The gauge symmetries are broken down to those of the minimal supersymmetric standard model which is the effective theory below 1016 GeV. The combination of the U(1)X family symmetry and the Pati-Salam gauge group leads to a successful and predictive set of Yukawa textures involving both kinds of texture zeroes. We discuss both symmetric and non-symmetric textures in models of this kind, and in the second case perform a detailed numerical fit to the charged fermion mass. (author)