If we insist on SU(3) ⊗ SU(3) classification for hadrons, in the presence of the known low-lying multiplets, we are led to models of the following nature: Before spontaneous breakdown, we have two commuting gauge groups, hadronic and leptonic. This divides such models into three sectors: hadrons, leptons, and a third unconventional set of (presumably high-mass) scalar mesons which serve to connect the two "known" worlds. Spontaneous breakdown induces appropriate masses and all usual strong, weak, and electromagnetic couplings. Intimate connections are seen between these three fundamental forces.

• Received 6 November 1972

DOI:https://doi.org/10.1103/PhysRevD.7.1233