Measurement of αs from energy-energy correlations at the Z0 resonance

Abstract

We determine the strong coupling αs from a comprehensive study of energy-energy correlations (EEC) and their asymmetry (AEEC) in hadronic decays of Z0 bosons collected by the SLD experiment at SLAC. The data are compared with all four available predictions of QCD calculated up to O(α2s) in perturbation theory, and also with a resummed calculation matched to all four of these calculations. We find large discrepancies between a, values extracted from the different O(α2s) calculations. We also find a large renormalization scale ambiguity in αs determined from the EEC using the 0(α2s) calculations; this ambiguity is reduced in the case of the AEEC and is very small when the matched calculations are used. Averaging over all calculations, and over the EEC and AEEC results, we obtain αs(M2z) = 0.124+0.003-0.004(expt.)±0.009(theory).