HEAVY TOP IN AN E(6)MODEL FOR FERMIONIC MASSES AND MIXING

We present a model for the fermionic masses in the E6 GUT using loop diagrams involving superheavy and gauge bosons. Those corrections add off-diagonal entries to the diagonal (proportional to each other) tree-level mass matrices. In addition to the corrections induced via nu(R) considered in the previous version, new genuine E6 contributions are required. Those involve the neutral, SO(10) invariant, lepton N and allow for solutions with large top mass (up to 250 GeV). Studying then in detail the allowed breaking chains of E6 the possible solutions are restricted and large values of m(t) are favoured. We obtain for those chains m(t,phys) greater-than-or-similar-to 100 GeV and in one special case 105 GeV less-than-or-similar-to m(t,phys) less-than-or-similar-to 125 GeV. The masses and mixing-angles of the light neutrinos are fixed, in the model, by the parameters of the quark sector. Large neutrino mixing is correlated with large m(t). An explanation of the solar neutrino puzzle a la MSW requires an intermediate scale around 10(12) GeV - the right one for unification in terms of the recent LEP results. At the same time, the corresponding nu(mu)-nu(tau) mixing and masses account for the depletion of the atmospheric nu(mu) flux observed recently by Kamiokande II and IMB.