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A straightforward SU(3) ×{} U(1) model in which there is effectively one new neutral-current parameter (denoted by R) is shown to give the canonical neutrino neutral-current predictions for all values of R. For small R the "low-energy" theory is essentially SU(2) ×{} U(1) while for R of the order of one it has a much richer "low-energy" gauge-boson mass spectrum. Even in the latter case, the predicted e-d asymmetry agrees with experiment. It is interesting that the atomic-physics parity violation depends sensitively on R.
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Singer et al. (1980) studied this question.
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