MODELS OF EXTENDED PATI-SALAM GAUGE-SYMMETRY

The possibility of constructing nonminimal models of the Pati-Salam type is investigated. The most interesting examples are found to have an SU(6) X SU(2)L X SU(2)R gauge invariance. Two interesting symmetry-breaking patterns are analyzed: one leading to the theory of SU(5) color at an intermediate scale, the other to the quark-lepton symmetric model. In both cases there is ample room for new physics in the interesting energy range of 100 GeV to a few TeV. We also identify a new candidate for dark matter.