Measurements of Inclusive W and Z Cross Sections in p-pbar Collisions at sqrt{s} =1.96 TeV
Abstract
We report the first measurements of inclusive W and Z boson cross sections times the corresponding leptonic branching ratios for p-pbar collisions at sqrt{s}=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 pm 4.3 pb-1. We test e-mu lepton universality in W decays by measuring the ratio of the wmnu to wenu cross sections and determine a value of 0.998 pm 0.004(stat.) pm 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 sigmabrppwln=2.775 pm 0.010(stat.) pm 0.053(syst.) pm 0.166(lum.) nb and sigmabrppzgll=254.9 pm 3.3(stat.) pm 4.6(syst.) pm 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 wlnu to zll cross sections taking all correlations among channels into account and obtain R=10.92 pm 0.15(stat.) pm 0.14(syst.) including a correction for the virtual photon exchange component in our measured zgll cross section. Based on the measured value of R, we extract values for the W leptonic branching ratio, Br(wlnu)=0.1089 pm 0.0022; the total width of the W boson, Gamma(W)=2079 pm 41 MeV; and the ratio of W and Z boson total widths, Gamma(W)/Gamma(Z)=0.833 pm 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 Vcs CKM matrix element, |Vcs|=0.967 pm 0.030.Keywords
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