We build a model to describe neutrinos based on strict hierarchy, incorporating as much as possible, the latest known data, for Delta(sol) and Delta(atm), and for the mixing angles determined from neutrino oscillation experiments, including that from KamLAND. Since the hierarchy assumption is a statement about mass ratios, it lets us obtain all three neutrino, masses. We obtain a mass matrix, M-nu and a mixing matrix, U, where both M-nu and U are given in terms of powers of Lambda, the analog of the Cabibbo angle lambda in the Wolfenstein representation, and two parameters, rho and kappa, each of order one. The expansion parameter, Lambda, is defined by Lambda(2) = m(2)/m(3) = rootDelta(sol)/Delta(atm) approximate to 0. 16, and rho expresses our ignorance of the lightest neutrino mass m(1), (m(1) = rhoDelta(4)m(3)), while kappa scales S-13 to the experimental upper limit, S-13 = kappaDelta(2) approximate to 0.16kappa. These matrices are similar in structure to those for the quark and lepton families, but with Lambda about 1.6 times larger than the lambda for the quarks and charged leptons. The upper limit for the effective neutrino mass in double beta-decay experiments is 4 x 10(-3) eV if S13 = 0 and 6 x 10-3 eV if s(13) is maximal. The model, which is fairly unique, given the hierarchy assumption and the data, is compared to supersymmetric extension and texture zero models of mass generation. (C) 2003 Elsevier B.V. All rights reserved. References: 24
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