FERMION MASSES, MIXING ANGLES, AND SUPERSYMMETRIC SO(10) UNIFICATION

We reanalyze the problem of fermion masses in supersymmetric SO(10) gr and unified models. In the minimal model, both low energy Higgs double ts belong to the same 10 representation of SO(10), implying the unific ation not only of the gauge but also of the third generation Yukawa co uplings. These models predict large values of tan beta similar to 50. In this paper we study the effects of departing from the minimal condi tions in order to see if we can find models with a reduced value of ta n beta. In order to maintain predictability, however, we try to do thi s with the addition of only one new parameter. We still assume that th e fermion masses arise from interactions of the spinor representations with a single 10 representation, but this 10 now only contains a part of the two light Higgs doublets. This enables us to introduce one new parameter omega = lambda(b)/lambda(t). For values of omega <double mu ch less than 1 we can in principle reduce the value of tan beta. In fa ct, omega is an overall factor which multiplies the down quark and cha rged lepton Yukawa matrices. Thus the theory is still highly constrain ed. We show that the first-generation quark masses and the CP violatio n parameter epsilon(K) are sufficient to yield strong constraints on t he phenomenologically allowed models. In the end, we find that large v alues of tan beta are still preferred.