A Half-Composite Standard Model at a TeV and Sin^2 theta_W

Abstract

We apply a recently proposed mechanism -- in which an SU(3) symmetry predicts the weak mixing angle -- to construct realistic theories with composite quarks and leptons at a TeV. Although the models are strongly coupled, they are reliably analyzed using complementarity and 't Hooft's anomaly matching. In the simplest models the right-handed fermions are composite, while the left-handed are elementary. Strong SU(2)_R forces give rise to 12-particle instanton-mediated processes. They violate baryon and lepton numbers by three units and result in spectacular multilepton and multijet events at the LHC. Models in which the leptons are in an SU(3)-triplet can be directly tested in muonium-antimuonium conversion experiments.