Hadronic decays of the Z 0 Boson: Jey physics and tests of QCD with OPAL

Abstract

Several QCD plus hadronisation models are compared to measured event shape distributions and the model parameters are adjusted to the data. QCD shower models provide a detailed description of hadroniv Z 0 decays and, with the same model parameters, of lower energy e +s − annihilation data as well. The momentum spectra of charged particles are consistent with the expectatioins of the soft gluon coherence and Local Parton Hadron Duality. From the measurement of jet production rates, the strong coupling constant is determined to be, in second order perturbation theory, α s(M Z) = 0.116 ± 0.016. Jet production rates and 4-jet angular correlations provide evidence for the running of α s and for the nonabelian structure of QCD.