par Abdallah, Jalal Mohamad;Bertrand, Daniel 
;Wickens, John H. ; [et al.]
Référence European Physical Journal C. Particles and Fields, 44, 3, page (311-331)
Publication Publié, 2005
;Wickens, John H. ; [et al.]Référence European Physical Journal C. Particles and Fields, 44, 3, page (311-331)
Publication Publié, 2005
Article révisé par les pairs
| Résumé : | 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 CA/CF with the result CA/CF = 2.261 ± 0.014stat. ± 0.036exp. ± 0.066theo. 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 twogluon colour-singlet states over a wide energy range. The ratios r = Ngg(s)/Nqq̄(s) of the gluon and quark multiplicities and r(1) = N′gg(s)/N′qq̄(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). © Springer-Verlag / Società Italiana di Fisica 2005. |
