B-L AS THE 4TH COLOR WITHIN AN SU(2)LXU(1)RXU(1) MODEL

Quark-lepton correspondence and the corresponding interpretation of B-L as the fourth color are combined in an SU(2)L×U(1)R×U′(1) electroweak model. The right-handed neutrino interactions are automatically suppressed and the standard model is recovered up to a desirable first-order fine structure. A fundamental distinction is established between the real Weinberg angle and its effective (measured) values. For neutrino interactions, our predictions are in general of the Weinberg-Salam (WS) type, only with the effective replacement sin2θW→sin2θWeff such that (a) sin2θWeff (purely leptonic processes) >sin2θWeff (νq scattering), and (b) for sin2θW=14 one can still have a lower value for the weighted average of sin2θWeff. Our expressions for the asymmetry parameter in electron-induced reactions agree with those of the WS model up to a second-order term. The additional neutral gauge boson is expected to be only 1 order of magnitude heavier than W±. We argue that the present neutral-current experimental data are not capable of distinguishing between the standard and the present models. Finally we discuss the possibility of embedding our model in a unified gauge theory, showing that only spinorial SO(4k+2) theories are available for this purpose. © 1979 The American Physical Society.