A measurement of energy correlations and a determination of αs( M2Z 0) e +e - annihilations at √ s=91 GeV

Abstract

From an analysis of multi-hadron events from Z 0 decays, values of the strong coupling constant α s( M 2 Z 0)=0.131±0.006 (exp)±0.002(theor.) and α s( M z 0 2) = −0.009 +0.007(exp.) −0.002 +0.006(theor.) are derived from the energy-energy correlation distribution and its asymmetry, respectively, assuming the QCD renormalization scale μ= M Z 0 . The theoretical error accounts for differences between O( α 2 s) calculations. A two parameter fit Λ MS and the renormalization scale μ leads to Λ MS =216±85 MeV and μ 2 s =0.027±0.013 or to α s( M 2 Z 0 )=0.117 +0.006 −0.008(exp.) for the energy-energy correlation distribution. The energy-energy correlation asymmetry distribution is insensitive to a scale change: thus the α s value quoted above for this variable includes the theoretical uncertainty associated with the renormalization scale.