Measurement of the charged multiplicities in B, C and light quark events from Z0 decays

Average charged multiplicities have been measured separately in b, c and light quark (u, d, s) events from Z0 decays measured in the SLD experiment. Impact parameters of charged tracks were used to select enriched samples of b and light quark events, and reconstructed charmed mesons were used to select c quark events. We measured the charged multiplicities: nuds = 20.21 ± 0.10 (stat.) ± 0.22 (syst.), nc = 21.28 ± 0.46 (stat.)+0−04136 (syst.) and nb = 23.14 ± 0.10 (stat.)+0−03837 (syst.), from which we derived the differences between the total average charged multiplicities of c or b quark events and light quark events: ∆nc = 1.07 ± 0.47 (stat.)+0−03630 (syst.) and ∆nb = 2.93 ± 0.14 (stat.)+0−03029 (syst.). We compared these measurements with those at lower center-of-mass energies and with perturbative QCD predictions. These combined results are in agreement with the QCD expectations and disfavor the hypothesis of flavor-independent fragmentation.