Bimaximal mixing in an SO(10) minimal Higgs model

An SO(10) SUSY GUT model was previously presented based on a minimal set of Higgs fields. The quark and lepton mass matrices derived fitted the data e xtremely well and led to large v(mu) - v(tau) mixing in agreement with the atmospheric neutrino data and to the small-angle MSW solution for the solar neutrinos. Here we show how a slight modification leading to a non-zero up quark mass can result in bimaximal mixing for the atmospheric and solar ne utrinos. The "just-so'' vacuum solution is slightly favored over the large- angle MSW solution on the basis of the hierarchy required for the right-han ded Majorana matrix and the more nearly-maximal mixing angles obtained. (C) 1999 Published by Elsevier Science B.V. All rights reserved.