A Possible Su(4)c X Su(3)f X U(1) Model*

An anomaly free model of strong and electro-weak interactions involving leptons and quarks in the SU(4) x Slam x U(1) gauge theory is C constructed. After spontaneous symmetry breaking, it reduces itself into the quantum chromodynamics for strong interactions and a broken SU(3) x U(1) model for electro-weak interactions. As a limiting case it gives the same results as those of the Weinberg-Salam model in the low energy region. The Weinberg angle is bounded by sin2eW < l/4 and becomes slightly less than 30' in the limiting case. Below the mass scale.of SU(4)c breaking there exists an inequality between Weinberg angle and the strong coupling constant, which is consistent with experiments. A correction to the neutral current of Weinberg-Salam model is suggested. (Submitted to Phys. Rev. D) * Work supported in part by the U.S. Department of Energy, contract DE-AC03-76SF00515 and in part by the People's Republic of China. t Permanent address.