AN SO(10) SOLUTION TO THE PUZZLE OF QUARK AND LEPTON MASSES

It is shown that almost all features of the quark and lepton masses can be satisfactorily and simply explained without family symmetry, including the threefold mass hierarchy among the generations, and the relations m(tau)(0) congruent to m(b)(0), m(mu)(0) congruent to 3m(s)(0), m(e)(0) congruent to 1/3m(d)(0), m(u)(0)/m(t)(0), much less than m(d)(0)/m(b)(0), tan theta(c) congruent to root m(d)(0)m(s)(0), V-cb much less than root m(s)(0)/m(b)(0), and V-ub similar to BcbVus. Various Various aspects of the group theory of SO(10) play an essential role in explaining these relations. There are distinctive and testable predictions for tan beta and the neutrino mixing angles.