Lepton number as the fourth "color"
Abstract
Universal strong, weak, and electromagnetic interactions of leptons and hadrons are generated by gauging a non-Abelian renormalizable anomaly-free subgroup of the fundamental symmetry structure $\mathrm{SU}{(4)}_{L}\ifmmode\times\else\texttimes\fi{}\mathrm{SU}{(4)}_{R}\ifmmode\times\else\texttimes\fi{}\mathrm{SU}({4}^{\ensuremath{'}})$, which unites three quartets of "colored" baryonic quarks and the quartet of known leptons into 16-folds of chiral fermionic multiplets, with lepton number treated as the fourth "color" quantum number. Experimental consequences of this scheme are discussed. These include (1) the emergence and effects of exotic gauge mesons carrying both baryonic as well as leptonic quantum numbers, particularly in semileptonic processes, (2) the manifestation of anomalous strong interactions among leptonic and semileptonic processes at high energies, (3) the independent possibility of baryon-lepton number violation in quark and proton decays, and (4) the occurrence of ($V+A$) weak-current effects.