Gauge models of theVV+AAtype and their effective neutrino interactions

We display, and compare with neutrino data, all possible gauge models with exactly two diagonal Z bosons, such that the neutral-current interaction of the usual quarks and leptons is of the form $VV+AA$ thereby conserving parity in atomic physics. Only three solutions are found to be consistent with data. One is the "left-right" or "ambidexterous" SU(2)L×SU(2)R×U(1) model which reduces to the standard SU(2) ×{} U(1) model; the other two are based on SU(3) ×{} U(1) and one of them reduces to an SU(2) ×{} U(1) model with a (u, b)R doublet. These latter solutions are only obtainable by abandoning the usual quark-lepton symmetry that was assumed by one of us in an earlier paper.