An Exceptional Electroweak Model

We consider a gauge extension of the electroweak sector of the Standard Model based on the group G_2 x SU(2)x U(1). The exceptional group 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 an SU(3) electroweak model in which a vector-like 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.