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In the first analysis the ratio of 2-jet
to 1-jet events was measured and alpha_s was extracted as a function of
the virtuality Q2 of the photon. The figure shows this measurement which
confirms the running of the strong coupling constant that is predicted
by perturbative QCD. |
 |
In the second analysis the 2-jet rate
was measured as a function of the threshold parameter that indicates formation
of two jets. This measurement of alpha_s is shown in the figure together
with the uncertainties in the measurement. |
Both measurements of alpha_s were extrapolated to the Z-boson mass
and agree well with the values of other experiments.
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