Abstract:
We report the first measurements of inclusive W and Z boson cross-sections times the corresponding leptonic branching ratios for p anti-p collisions at s**(1/2) = 1.96 TeV based on the decays of the W and Z bosons into electrons and muons. The data were recorded with the CDF II detector at the Fermilab Tevatron and correspond to an integrated luminosity of 72.0 +/- 4.3 pb-1. We test e-mu lepton universality in W decays by measuring the ratio of the W --> mu nu to W --> e nu cross sections and determine a value to 0.991 +/- 0.004(stat.) +/- 0.011(syst.) for the ratio of W - l - nu couplings (g_mu/g_e). Since there is no sign of non-universality, we combine our cross-section measurements in the different lepton decay modes and obtain sigma_W x Br(p anti-p --> W --> l nu) = 2.749 +/- 0.010(stat.) +/- 0.053(syst.) +/- 0.165(lum.) nb and sigma_gamma*/Z x BR(p anti-p --> gamma*/Z --> ll) = 254.9 +/- 3.3(stat.) +/- 4.6(syst.) +/- 15.2(lum.) pb for dilepton pairs in the mass range between 66 GeV/c2 and 116 GeV/c2. We compute the ratio R of the W --> l nu to Z --> ll cross section taking all correlations among channels into account and obtain R = 10.84 +/- 0.15(stat.) +/- 0.14(syst.) including a correction for the virtual photon exchange component in our measured gamma*/Z --> ll cross section. Based on the measured value of R, we extract values for the W leptonic branching ratio, Br(W --> l nu) = 0.1082 +/- 0.0022; the total width of the W boson, Gamma(W) = 2092 +/- 42 MeV; and the ratio of W and Z boson total widths, Gamma(W)/Gamma(Z) = 0.838 +/- 0.017. In addition, we use our extracted value of Gamma(W) whose value depends on various electroweak parameters and certain CKM matrix elements to constrain the V_cs CKM matrix element, |V_cs| = 0.976 +/- 0.030.
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