Upper Bounds on Top Quark Mass,Z Boson Decay Widths and Mass Ratio MW/MZ

In this paper we made a comprehensive analysis of some latest esperimental data-the Z boson decay widths, the mass ratio M_W/M_Z and effective vector coupling constant g_v, within the framework of standard model. We considered the 0(α_s²), order QCD corrections in tlte calculation of T_h and T_z. The analysis shows that the mass ratio (M_W/M_Z)² is rather sensitive to the change of the strong coupling constant α_s(M_Z), and the smaller value α_s(M_Z)≤0.128 is preferred. The upper bounds on top quark Inass M_t are obtained from different analyses. The final averaged result is M_t= 102 37 GeV, or M_t< 186 GeV at 95% C.L. for Higgs boson mass M_H in the range of 50～1000 GeV.