Minimum four-color quark-lepton symmetrical model and its limits on Z' boson mass

A minimal quark-lepton symmetry model of the unification of the strong and electroweak interaction as the minimal extension of the standard model containing the four-color quark-lepton symmetry is discussed. The corresponding experimental data are shown to be compatible with the existence of the relatively light Z-boson originating from the four-color quark-lepton symmetry