Measurement of alpha(s) in e(+)e(-) annihilation at E(cm) = 29 GeV
Abstract
A measurement of the strong coupling constant alpha(sub s) using the event-shape variable y(sub 3) (the differential two-jet rate) in the reaction e(+)e(-) yields hadrons is presented. The analysis is based on data from the TPC/Two-Gamma detector at the PEP e(+)e(-) storage ring taken between 1984 and 1986 at a center-of-mass energy of E(sub cm) = 29 GeV. A value of alpha(sub s)(29 GeV) = 0.160 +/- 0.012 is obtained, where the error is the quadratic sum of experimental and theoretical uncertainties. The procedure for determining alpha(sub s) is the same as that used by the ALEPH and TOPAZ experiments, which allows for a consistent comparison of the alpha(sub s) values obtained at different center-of-mass energies. The observed energy dependence 'running' of alpha(sub s) is found to be in good agreement with the QCD prediction, and is clearly incompatible with a constant value.
- Publication:
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Presented at the 27th International Conference on High Energy Physics
- Pub Date:
- July 1994
- Bibcode:
- 1994hep..confS..21B
- Keywords:
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- Electron-Positron Pairs;
- Hadrons;
- Monte Carlo Method;
- Positron Annihilation;
- Quantum Chromodynamics;
- Strong Interactions (Field Theory);
- Algorithms;
- Center Of Mass;
- Computer Programs;
- Models;
- Nuclear Binding Energy;
- Perturbation Theory;
- Photon-Electron Interaction;
- Storage Rings (Particle Accelerators);
- Atomic and Molecular Physics