NEUTRINO MASSES AND B-TAU UNIFICATION IN THE SUPERSYMMETRIC STANDARD MODEL

There are several indications that the Majorana masses of the right-handed neutrino components, M(R), are at the intermediate scale: M(R) similar to (10(10) - 10(12)) GeV or even lighter. The renormalization effects due to large Yukawa couplings of neutrinos from region of momenta M(R) less than or similar to q less than or similar to M(G) are studied in the supersymmetric standard model. It is shown that neutrino renormalization effect can increase the m(b)/m(t)au ratio up to (10-15)%. This strongly disfavours m(b)-m(t)au unification for low values of tan beta < 10 especially at large values of alpha(S). Lower bounds on M(R) and tan beta from the b - tau unification condition were found. The implications of the results to the see-saw mechanism of the neutrino mass generation are discussed.