The charged particle multiplicity in hadronic three-jet events from Z decays is investigated. The topology dependence of the event multiplicity is found to be well described by a modified leading logarithmic prediction. A parameter fit of the prediction to the data yields a measurement of the colour factor ratio C-A/C-F with the result C-A/C-F = 2.261 +/- 0.014(stat). +/- 0.036(exp). +/- 0-066(theo). in agreement with the SU(3) expectation of QCD. The quark-related contribution to the event multiplicity is subtracted from the three-jet event multiplicity resulting in a measurement of the multiplicity of two-gluon colour-singlet states over a wide energy range. The ratios r = N-gg(s)/Ng (g) over bar (s) of the gluon and quark multiplicities and r((1)) = N'(gg)(s)/N'g (g) over bar (s) of their derivatives are compared with perturbative calculations. While a good agreement between calculations and data is observed for r((1)), larger deviations are found for r indicating that non-perturbative effects are more important for r than for r((1)).

Abdallah, J., Abreu, P., Adam, W., Adzic, P., Albrecht, T., Alderweireld, T., et al. (2005). Charged particle multiplicity in three-jet events and two-gluon systems. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 44(3), 311-331 [10.1140/epjc/s2005-02390-x].

Charged particle multiplicity in three-jet events and two-gluon systems

CALVI, MARTA;PAGANONI, MARCO;TABARELLI DE FATIS, TOMMASO;
2005

Abstract

The charged particle multiplicity in hadronic three-jet events from Z decays is investigated. The topology dependence of the event multiplicity is found to be well described by a modified leading logarithmic prediction. A parameter fit of the prediction to the data yields a measurement of the colour factor ratio C-A/C-F with the result C-A/C-F = 2.261 +/- 0.014(stat). +/- 0.036(exp). +/- 0-066(theo). in agreement with the SU(3) expectation of QCD. The quark-related contribution to the event multiplicity is subtracted from the three-jet event multiplicity resulting in a measurement of the multiplicity of two-gluon colour-singlet states over a wide energy range. The ratios r = N-gg(s)/Ng (g) over bar (s) of the gluon and quark multiplicities and r((1)) = N'(gg)(s)/N'g (g) over bar (s) of their derivatives are compared with perturbative calculations. While a good agreement between calculations and data is observed for r((1)), larger deviations are found for r indicating that non-perturbative effects are more important for r than for r((1)).
Articolo in rivista - Articolo scientifico
high energy collider; LEP; DELPHI
English
2005
44
3
311
331
none
Abdallah, J., Abreu, P., Adam, W., Adzic, P., Albrecht, T., Alderweireld, T., et al. (2005). Charged particle multiplicity in three-jet events and two-gluon systems. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 44(3), 311-331 [10.1140/epjc/s2005-02390-x].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/46579
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