An analysis of global event-shape variables has been carried out for the reaction e +e - -> Z 0->hadrons to measure the strong coupling constant alpha_s. This study is based on 52720 hadronic events obtained in 1989/90 with the ALEPH detector at the LEP collider at energies near the peak of the Z-resonance. In order to determine alpha_s, second order QCD predictions modified by effects of perturbative higher orders and hadronization were fitted to the experimental distributions of event-shape variables. From a detailed analysis of the theoretical uncertainties we find that this approach is best justified for the differential two-jet rate, from which we obtain alpha_s((M_Z)^2)=0.121 +/- 0.002(stat.) +/- 0.003(sys.) +/- 0.007(theor.) using a renormalization scale omega=1/2M_Z. The dependence of alpha_s((M_Z)^2) on omega is parameterized. For scales m_b

D., D., B., D., C., G., J., L., M., M., R., A., et al. (1991). Measurement of the strong coupling constant alfa_s from global event-shape variables of hadronic Z decays. PHYSICS LETTERS. SECTION B, 255(4), 623-633 [10.1016/0370-2693(91)90278-X].

Measurement of the strong coupling constant alfa_s from global event-shape variables of hadronic Z decays

BOTTIGLI, UBALDO;CIOCCI, MARIA AGNESE;MARROCCHESI, PIER SIMONE;
1991-01-01

Abstract

An analysis of global event-shape variables has been carried out for the reaction e +e - -> Z 0->hadrons to measure the strong coupling constant alpha_s. This study is based on 52720 hadronic events obtained in 1989/90 with the ALEPH detector at the LEP collider at energies near the peak of the Z-resonance. In order to determine alpha_s, second order QCD predictions modified by effects of perturbative higher orders and hadronization were fitted to the experimental distributions of event-shape variables. From a detailed analysis of the theoretical uncertainties we find that this approach is best justified for the differential two-jet rate, from which we obtain alpha_s((M_Z)^2)=0.121 +/- 0.002(stat.) +/- 0.003(sys.) +/- 0.007(theor.) using a renormalization scale omega=1/2M_Z. The dependence of alpha_s((M_Z)^2) on omega is parameterized. For scales m_b
1991
D., D., B., D., C., G., J., L., M., M., R., A., et al. (1991). Measurement of the strong coupling constant alfa_s from global event-shape variables of hadronic Z decays. PHYSICS LETTERS. SECTION B, 255(4), 623-633 [10.1016/0370-2693(91)90278-X].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11365/35628
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