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" $\mathrm{SU}{\mathrm{}\left(2\right)\mathrm{}}_L\times \mathrm{SU}{\mathrm{}\left(2\right)\mathrm{}}_R\times \mathrm{U}\mathrm{}\left(1\right)\mathrm{}$ 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.