A MEASUREMENT OF Rμ = σ(W → μv)/σ(Z^0→ μ^+ μ^-) IN PP ̅ COLLISIONS AT √S = 1.8 TEV
A measurement in the muon channel of the ratio of W and Z production cross sections times branching ratios yields Rμ = σ(W → μv)/σ(Z^0→ μ^+ μ^-) = 9.8 ± 1.1(stat) ± 0.4(syst), where the statistics of the Z sample is the dominant uncertainty. The individual cross sections times branching ratios are σ(pp ̅ → W → μv) = 2.21 ± 0.07(stat) ± 0.14(syst) ± 0.15(lum) nb and σ(pp ̅ → Z^0→ μ^+ μ^-) = 0.226 ± 0.022( stat)± 0.018( syst) ± 0.015( lum) nb. Combining with previous CDF results in the electron channel yields the overall results R_1 = 10.0 ± 0.6(stat) ± 0.4(syst), σ(W → lv) = 2.21 ± 0.04(stat) ± 0.13(syst) ± 0.15(lum) nb, and σ(Z^0→ ll) = 214 ± 11(stat) ± 14(syst) ± 15(lum) pb. Using Standard Model assumptions we deduce the W inverse branching ratio and width, and a lower bound on the top quark mass of 45 GeV / c^2 (95% CL) which is independent of the decay mode. Lepton universality is confirmed in this energy domain. All results are in agreement with standard model predictions.
time branching ratios, computational physics, electron channel, Standard Model, Lepton universality
University of Illinois - Urbana-Champaign
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