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Average charged multiplicities have been measured separately for[ital b, c] and light quark ([ital u, d, s]) events from Z[sup 0] decays at SLD. Impact parameters of charged tracks were used to select enriched samples of[ital b] and light quark events. We measured the charged multiplicities:[bar[ital n]][sub[ital uds]]= 19.80[+-] 0.09 ([ital stat])[+-] 0.57 ([ital syst]), [bar[ital n]][sub[ital c]]= 21.17[+-] 0.44 ([ital stat])[+-] 1.01 ([ital syst]) and[bar[ital n]][sub[ital b]][+-]23.14[+-] 0.09 ([ital stat])[+-] 1.03 ([ital syst]) (PRELIMINARY), from which we derived the differences between the total average charged multiplicities of[ital c] or[ital b] quark events and light quark events:[delta][bar[ital n]][sub[ital c]]= 1.37[+-] 0.45 ([ital stat])[+-] 0.86 ([ital syst]) and[delta][bar[ital n]][sub[ital b]]= 3.34[+-] 0. 13 ([ital stat])[+-] 0.77 ([ital syst]) (PRELIMINARY). We compared these measurements with those at lower center-of-mass energies and with QCD predictions.
Average charged multiplicities have been measured separately in b, c and light quark (u, d, s) events from Z[sup 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:[anti n][sub uds]= 20.21[+-] 0.10 (stat.)[+-] 0.17 (syst.), [anti n][sub c]= 21.28[+-] 0.46 (stat.)[sub -0.33][sup+0.38] (syst.) and[anti n][sub b]= 23.14[+-] 0.10 (stat.)[sub -0.34][sup+0.35] (syst.), from which we derived the differences between the total average charged multiplicities of c or b quark events and light quark events:[Delta][anti n][sub c]= 1.07[+-] 0.47 (stat.)[sub -0.30][sup+0.36] (syst.) and[Delta][anti n][sub b]= 2.93[+-] 0.14 (stat.)[sub -0.29][sup+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.
Average charged multiplicities have been measured separately in b, c and light quark (u, d, s) events from Z° 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: {anti n}{sub uds} = 20.21 ± 0.10 (stat.) ± 0.17 (syst.), {anti n}{sub c} = 21.28 ± 0.46 (stat.){sub -0.33}{sup +0.38} (syst.) and {anti n}{sub b} = 23.14 ± 0.10 (stat.){sub -0.34}{sup +0.35} (syst.), from which we derived the differences between the total average charged multiplicities of c or b quark events and light quark events: [Delta]{anti n}{sub c} = 1.07 ± 0.47 (stat.){sub -0.30}{sup +0.36} (syst.) and [Delta]{anti n}{sub b} = 2.93 ± 0.14 (stat.){sub -0.29}{sup +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.
Average charged multiplicities have been measured separately for {ital b, c} and light quark ({ital u, d, s}) events from Z° decays at SLD. Impact parameters of charged tracks were used to select enriched samples of {ital b} and light quark events. We measured the charged multiplicities: {bar {ital n}}{sub {ital uds}} = 19.80 ± 0.09 ({ital stat}) ± 0.57 ({ital syst}), {bar {ital n}}{sub {ital c}} = 21.17 ± 0.44 ({ital stat}) ± 1.01 ({ital syst}) and {bar {ital n}}{sub {ital b}}±23.14 ± 0.09 ({ital stat}) ± 1.03 ({ital syst}) (PRELIMINARY), from which we derived the differences between the total average charged multiplicities of {ital c} or {ital b} quark events and light quark events: [delta]{bar {ital n}}{sub {ital c}} = 1.37 ± 0.45 ({ital stat}) ± 0.86 ({ital syst}) and [delta]{bar {ital n}}{sub {ital b}} = 3.34 ± 0. 13 ({ital stat}) ± 0.77 ({ital syst}) (PRELIMINARY). We compared these measurements with those at lower center-of-mass energies and with QCD predictions.
Using the precision vertex detectors of the Mark 2 at the SLC, an impact parameter tag was developed to select a sample of hadronic Z° decays enriched in its fraction of bottom quark events. The nominal tagging method requires that there be at least three tracks whose impact parameters are inconsistent with the track having originated at the electron-position interaction point. A tagging efficiency for b{bar b} events of 50% with a enriched sample purity of 85% was achieved. This impact parameter tag was used to measure the fraction hadronic Z° decays which produce b{bar b} events, F{sub b}. It is found that F{sub b} = 0.232{sub -0.045}{sup +0.053} (stat) {sub -0.021}{sup +0.025} (syst). This result is consistent with those found using other tagging methods as well as the Standard Model prediction of 0.217. The b{bar b}-enriched event sample was also used to measure the difference between the average charged multiplicity of b{bar b} events and that of all hadronic Z° decays,?{bar n}{sub b} = 2.11 {plus minus} 1.82(stat) {plus minus} 0.57(syst). Using previous measurements of the total hadronic charged multiplicity, the corresponding total multiplicity for b{bar b} events is {bar n}{sub b}=23.05 {plus minus} 1.82 (stat) {plus minus} 0.60 (syst). Subtracting the contribution to the multiplicity from B hadron decays yields the multiplicity of the b{bar b} non-leading system, {bar n}{sub nl} = 12.04 {plus minus} 1.82 (stat) {plus minus} 0.63(syst). Comparing this non-leading multiplicity to the total hadronic multiplicity data at lower energy supports the hypothesis that the non-leading particle production is independent of the flavor of the initial quarks.
We present preliminary evidence for leading particle production in hadronic decays of the Z[sup 0] to light quark pairs using 150,000 events recorded in the SLD experiment at SLAC. The highly polarized electron beam produced by the SLC is used to tag quark and antiquark jets, and a signed impact parameter technique is employed to reject heavy flavor events. Charged hadrons are identified in the SLD Cherenkov Ring Imaging Detector (CRID) and[Lambda]/[bar[Lambda]] are reconstructed using their charged decay modes. In a high purity sample of quark jets, the baryon momentum spectrum is harder that that of the antibaryon, and conversely for a sample of antiquark jets, supporting the hypothesis that the faster particles in jets are more likely to carry the primary quark or antiquark from the Z[sup 0] decay. Similarly, more high momentum K[sup -] that K[sup+] are observed in quark jets and conversely for antiquark jets, consistent with the hypothesis that leading K[sup[+-]] are produced predominantly in s[bar s] events rather than[ital u][bar[ital u]] events.
Using the precision vertex detectors of the Mark 2 at the SLC, an impact parameter tag was developed to select a sample of hadronic Z° decays enriched in its fraction of bottom quark events. The nominal tagging method requires that there be at least three tracks whose impact parameters are inconsistent with the track having originated at the electron-position interaction point. A tagging efficiency for b{bar b} events of 50% with a enriched sample purity of 85% was achieved. This impact parameter tag was used to measure the fraction hadronic Z° decays which produce b{bar b} events, F{sub b}. It is found that F{sub b} = 0.232{sub -0.045}{sup +0.053} (stat) {sub -0.021}{sup +0.025} (syst). This result is consistent with those found using other tagging methods as well as the Standard Model prediction of 0.217. The b{bar b}-enriched event sample was also used to measure the difference between the average charged multiplicity of b{bar b} events and that of all hadronic Z° decays, [delta]{bar n}{sub b} = 2.11 ± 1.82(stat) ± 0.57(syst). Using previous measurements of the total hadronic charged multiplicity, the corresponding total multiplicity for b{bar b} events is {bar n}{sub b}=23.05 ± 1.82 (stat) ± 0.60 (syst). Subtracting the contribution to the multiplicity from B hadron decays yields the multiplicity of the b{bar b} non-leading system, {bar n}{sub nl} = 12.04 ± 1.82 (stat) ± 0.63(syst). Comparing this non-leading multiplicity to the total hadronic multiplicity data at lower energy supports the hypothesis that the non-leading particle production is independent of the flavor of the initial quarks.