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.
Measurements of the strong coupling constant and the QCD colour factors using four-jet observables from hadronic Z decays / A. Heister et al.;V.Ciulli;E.Focardi. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - ELETTRONICO. - 27:(2003), pp. 1-17. [10.1140/epjc/s2002-01114-2]
Measurements of the strong coupling constant and the QCD colour factors using four-jet observables from hadronic Z decays
CIULLI, VITALIANO;FOCARDI, ETTORE
2003
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.I documenti in FLORE sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.