Precision tests of perturbative QCD at the neutral Z boson peak

A QCD analysis of hadronic decays of the ;The theoretical predictions for the renormalization scale ;The overall conclusion is that QCD is apparently a valid theory of strong interactions, and higher order calculations are indispensable to further improve the precision of these tests.;A special emphasis is given on estimating the theoretical uncertainties. The uncertainties due to the hadronization, parton virtuality, renormalization scale and the experimental systematics are estimated. The...