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T: Teilchenphysik
T 608: QCD IV
T 608.3: Talk
Thursday, March 13, 2003, 11:00–11:15, SFO11
αS and power corrections from JADE — •Pedro A. Movilla Fernández1, S. Bethke1, O. Biebel2, M. Blumenstengel1, S. Kluth1, C. Pahl1, and J. Schieck1 — 1Max-Planck-Institut für Physik, München — 2Ludwig-Maximilians-Universität, München
Tests of Quantum Chromodynamics (QCD) become substantially more stringent using e+e− annihilation data collected by the JADE experiment at PETRA (1979-1986). We present a state-of-the-art determination of the strong coupling constant αS at centre-of-mass energies √s =14 to 44 GeV based on O(αS2)+NLLA QCD predictions for various event shape observables. The calculations are found to describe reliably data at the lowest annihilation energies although non-perturbative contributions become important. Non-perturbative effects were estimated using LEP-tuned hadronisation models. The results are in good agreement with the QCD expectation for the running of αS which can be consistently combined into a representative value αS(MZ0)=0.1194−0.0068+0.0082.
We also investigated analytically calculated power corrections to event shapes as an alternative approach to describe non-perturbative effects to hadronic final states. The sensitivity to power corrections is increased due to the inclusion of the recently reanalysed JADE data at √s= 14 to 22 GeV. Except for the less inclusive observables (e.g. BW), the calculations are found to fit satisfactorily the event shape spectra. From global fits to the differential distributions from PETRA to LEP2 energies, αS and the only non-perturbative parameter α0 were measured to αS(MZ0)=0.1126−0.0048+0.0058 and α0(2 GeV)=0.542−0.068+0.090, respectively, and are found to be universal within the systematic uncertainties.