The interplay between neutrinos and charged leptons in the minimal SU(3)L x U(1)N gauge model

In the minimal SU(3)(L) x U(1)(N) gauge model with a global L-e-L-mu-L-tau (= L ') symmetry and a discrete Z(4) symmetry, it is found that the interplay between neutrinos and charged leptons contained in triplets of psi (i) = (v(L)(i), l(L)(i), l(L)(ci)) (i = 1,2,3) naturally leads to the large mixing angle (LMA) MSW solution. The model includes two (anti)sextet Higgs scalars, S-(0) with L ' = 0 and S(+) with L ' = 2, which, respectively, couple to psi (1)psi (2,3) for the electron mass and masses of atmospheric neutrinos and to psi (2,3)psi (2,3) for the mu- and tau -masses and one-loop radiative neutrino masses relevant to solar neutrinos. This mechanism is realized by utilizing an additional residual discrete symmetry supplied by explicitly broken L ', which guarantees the absence of tree-level neutrino mass terms of the psi (2,3)psi (2,3)-type. Pure rotation effects due to the diagonalization of neutrino and charged-lepton mass matrices are estimated to yield Deltam(circle dot)(2)/Deltam(atm)(2) less than or similar to (m(e)/m(mu))(3/2) = O(10(-4))but the radiative effects supersede the rotation effects to yield Deltam(circle dot)(2)/Deltam(atm)(2) = O(10(-2)) as the LMA solution. (C) 2001 Elsevier Science B.V. All rights reserved.