Fermion mass prediction from infra-red fixed points

Abstract

We argue that in a wide class of theories the fermion and soft supersymmetry breaking mass structure is largely determined by the infra-red fixed point structure of the theory lying beyond the standard model. We show how knowlege of the symmetries and multiplet content of this theory is sufficient to determine the infra-red structure, illustrating the idea for the case of a simple abelian family symetry. The resulting structure determines the fermion masses and mixing angles in terms of a restricted number of parameters.