We present a natural SU(2)×U(1)×SU(2)′ gauge model with low-energy predictions identical to those of the standard model, but which allows all gauge-boson masses to be above or straddling their standard values. We discuss the Higgs structure and its relationship to the naturalness of the model. Current measurements of the $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$ cross section set upper limits on the lightest $W$ and $Z$ masses of 89 and 116 GeV, respectively; from data on $e^{+}{e}^{-}\to \mathrm{hadrons}$, the corresponding limits $M_{W_1}<87\mathrm{}$ and $M_{Z_1}<108\mathrm{}$ GeV are deduced. Some high-energy predictions for the model are explored. The model is extended to $\mathrm{U}\mathrm{}\left(1\right)\mathrm{}\times \mathrm{SU}{\mathrm{}\left(2\right)\mathrm{}}^N$ with all possible SU(2)×U(1) Higgs doublets and SU(2)×SU(2) Higgs quartets.

• Received 21 September 1981

DOI:https://doi.org/10.1103/PhysRevD.25.1384