Electroweak Unification into a Five-Dimensional SU(3) at a TeV
  We apply a recently proposed mechanism for predicting the weak mixing angle to theories with TeV-size dimensions. "Reconstruction" of the associated moose (or quiver) leads to theories which unify the electroweak forces into a five dimensional SU(3) symmetry. Quarks live at an orbifold fixed point where SU(3) breaks to the electroweak group. A variety of theories -- all sharing the same successful prediction of the weak mixing angle -- emerges; they differ primarily by the spatial location of the leptons and the absence or presence of supersymmetry. A particularly interesting theory puts leptons in a Konopinski-Mahmoud triplet and suppresses proton decay by placing quarks and leptons on opposite fixed points. 
Savas Dimopoulos, David E. Kaplan, Neal Weiner