Determination of α s from energy-energy correlations measured on the Z 0 resonance

We present a study of energy-energy correlations based on 83 000 hadronic Z 0 decays. From this data we determine the strong coupling constant α s to second order QCD: α s(91.2 GeV)=0.121±0.004(exp.)±0.002(hadr.) -0.006 +0.009(scale)±0.006(theor.) from the energy-energy correlation and α s(91.2 GeV)=0.115±0.004(exp.) -0.004 +0.007(hadr.) -0.000 +0.002(scale) -0.005 +0.003(theor.) from its asymmetry using a renormalization scale μ 2=0.1 s. The first error (exp.) is the systematic experimental uncertainty, the statistical error is negligible. The other errors are due to hadronization (hadr.), renormalization scale (scale) uncertainties, and differences between the calculated second order corrections (theor.).