Unification via intermediate symmetry breaking scales with the quartification gauge group

Abstract

The idea of quark-lepton universality at high energies has been introduced as a natural extension to the standard model. This is achieved by endowing leptons with new degrees of freedom-leptonic color, an analogue of the familiar quark color. Grand and partially unified models which utilize this new gauge symmetry SU(3)ℓ have been proposed in the context of the quartification gauge group SU(3)4. Phenomenologically successful gauge coupling constant unification without supersymmetry has been demonstrated for cases where the symmetry breaking leaves a residual SU(2)ℓ unbroken. Though attractive, these schemes either incorporate ad hoc discrete symmetries and nonrenormalizable mass terms, or ac..