Model for the Stech mass matrix for quarks

Abstract
We present a theoretical derivation of the Stech Ansatz for the quark mass matrices within a supersymmetric SO(10) model. The model does not involve any horizontal discrete symmetries. Supersymmetry and dominance of the right-handed neutrino in the loop are crucial for the success of the model. We also comment on the solution of the strong CP problem in the context of this model.