Measurement of the partial widths of the Z into up- and down-type quarks

摘要

Using the entire OPAL LEP1 on-peak Z hadronic decay sample, Z --> qqgamma decays were selected by tagging hadronic final states with isolated photon candidates in the electromagnetic calorimeter. Combining the measured rates of Z --> qqgamma decays with the total rate of hadronic Z decays permits the simultaneous determination of the widths of the Z into up- and down-type quarks. The values obtained, with total errors, wereGamma(u) = 300(-18)(+19) MeV and Gamma(d) = 381(-12)(+12) MeV.The results are in good agreement with the Standard Model expectation. (C) 2004 Elsevier B.V. All rights reserved.