We consider a gauge extension of the electroweak sector of the standard model based on the group ${\mathrm{G}}_2\times \mathrm{SU}(2)\times \mathrm{U}(1)$. The exceptional group ${\mathrm{G}}_2$ is the smallest rank two group that contains SU(3) as a subgroup; the SU(3) prediction ${sin}^2{\theta }_w=1/4$ follows approximately in this model if the couplings of the additional SU(2) and U(1) factors are sufficiently large. We study the symmetry-breaking sector of the model, the bounds from precision electroweak constraints and the mass spectrum of exotic gauge bosons that may be produced at future colliders. We also discuss a SU(3) electroweak model in which a vectorlike sector is included explicitly to facilitate the decays of otherwise stable exotic states. The models considered here represent plausible extensions of the minimal SU(3) electroweak model with potentially distinctive TeV-scale phenomenology.

• Received 10 December 2007

DOI:https://doi.org/10.1103/PhysRevD.77.035011