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Measurements of the strong coupling constant and the QCD color factors using four jet observables from hadronic Z decays.

Research output: Contribution to journalJournal article

Published
<mark>Journal publication date</mark>03/2003
<mark>Journal</mark>European Physical Journal C: Particles and Fields
Issue number1
Volume27
Number of pages17
Pages (from-to)1-17
<mark>State</mark>Published
<mark>Original language</mark>English

Abstract

Data from annihilation into hadrons, taken with the ALEPH detector at the Z resonance, are analyzed. The four-jet rate is studied as a function of the resolution parameter and compared to next-to-leading order calculations combined with resummation of large logarithms. Angular correlations in four-jet events are measured and compared to next-to-leading order QCD predictions. With these observables two different measurements are performed. In a first analysis the strong coupling constant is measured from the four-jet rate yielding . In a second measurement the strong coupling constant and the QCD colour factors are determined simultaneously from a fit to the four-jet rate and the four-jet angular correlations, giving in good agreement with the expectation from QCD.