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Data from e(+)e(-) 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 alpha(S)(M(Z)) = 0.1170 +/- 0.0001(stat) +/- 0.0013(sys). 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 a(S)(M(Z)) = 0.119 +/- 0.006(stat) +/- 0.026(sys) C(A) = 2.93 +/- 0.14(stat) +/- 0.58(sys) C(F) = 1.35 +/- 0.07(stat) +/- 0.26(sys) 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 / Heister, A., Schael, S., Barate, R., De Bonis, I., Decamp, D., Goy, C., Lees, J.p., Merle, E., Minard, M.n., Pietrzyk, B., Boix, G., Bravo, S., Casado, M.p., Chmeissani, M., Crespo, J.m., Fernandez, E., Fernandez-Bosman, M., Garrido, L., Grauges, E., Martinez, M., et al.. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - STAMPA. - 27:1(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

Creanza D;Iaselli G;Maggi G;
2003

Abstract

Data from e(+)e(-) 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 alpha(S)(M(Z)) = 0.1170 +/- 0.0001(stat) +/- 0.0013(sys). 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 a(S)(M(Z)) = 0.119 +/- 0.006(stat) +/- 0.026(sys) C(A) = 2.93 +/- 0.14(stat) +/- 0.58(sys) C(F) = 1.35 +/- 0.07(stat) +/- 0.26(sys) in good agreement with the expectation from QCD.
2003
Measurements of the strong coupling constant, and the QCD colour factors using four-jet observables from hadronic Z decays / Heister, A., Schael, S., Barate, R., De Bonis, I., Decamp, D., Goy, C., Lees, J.p., Merle, E., Minard, M.n., Pietrzyk, B., Boix, G., Bravo, S., Casado, M.p., Chmeissani, M., Crespo, J.m., Fernandez, E., Fernandez-Bosman, M., Garrido, L., Grauges, E., Martinez, M., et al.. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - STAMPA. - 27:1(2003), pp. 1-17. [10.1140/epjc/s2002-01114-2]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11589/5798
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