A study of the recombination scheme dependence of jet production rates and of αs() in hadronicZ0 decays

Jet production rates in hadronicZ0 decays are studied using four different recombination schemes to define resolvable jets. The strong coupling constant αs($$M_{Z^0 } $$) is determined in fits of the correspondingO(αs2) QCD calculations to the differential 2-jet distributionsD2(y). Hadronisation corrections and renormalisation scale uncertainties are found to be different for each recombination scheme. Within their overall systematic uncertainties, the four schemes yield consistent values of αs($$M_{Z^0 } $$), leading to a final result of$$\alpha _s (M_{Z^0 } ) = 0.118 \pm 0.008.$$.The error includes the experimental uncertainties (±0.003), uncertainties of hadronisation corrections and of the degree of parton virtualities to which the data are corrected, as well as the uncertainty of choosing the renormalisation scale.