Measurement of the charged multiplicities in b, c and light quark events from Z(O) decays

Average charged multiplicities have been measured separately in b, c and light quark (u, d, s) events from Z(0) 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: <(n)over bar (uds)> = 20.21 +/- 0.10(stat.) +/- 0.22(syst.), <(n)over bar (c)> = 21.28 +/- 0.46(stat.)(-0.36)(+0.41)(syst.) and <(n)over bar (b)> = 23.14 +/- 0.10(stat.)(-0.37)(+0.38)(syst.), from which we derived the differences between the total average charged multiplicities of c or b quark events and light quark events: <Delta(n)over bar (c)> = 1.07 +/- 0.47(stat.)(-0.30)(+0.36)(syst.) and <Delta(n)over bar (b)> = 2.93 +/- 0.14(stat.)(-0.29)(+0.30)(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.