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We have studied the fragmentation process in Z[sup 0][yields] light-flavor (u[bar u], d[bar d], s[bar s]) events by measuring the differential cross sections for the production of the identified hadrons[pi][sup[+-]], K[sup[+-]], p/[bar p], K[sub s][sup 0], [Lambda][sup 0]/[bar[Lambda]][sup 0], K*[sup 0]/[bar K]*[sup 0] and[phi], and by performing a preliminary study of correlations in rapidity between pairs of identified[pi][sup[+-]], K[sup[+-]], and p/[bar p]. Short range charge correlations are observed between all combinations of these three hadron species. A strong long range correlation is observed between all combinations of these three hadron species. A strong long range correlation is observed for high-momentum charged kaon pairs, and weaker[pi][sup+][pi][sup -], [pi][sup+]K[sup -] and pK[sup -] correlations are observed. The SLC beam polarization is used to tag the quark hemisphere in each event, allowing the first study of rapidities signed such that positive rapidity is along the quark rather than antiquark direction. Distributions of signed rapidities and of ordered differences between signed rapidities provide new insights into leading particle production and several new tests of fragmentation models. We have used these correlation studies to perform a preliminary direct measurement of the parity violating coupling of the Z[sup 0] to strange quarks, A[sub s]. Our result is: A[sub s]= 0.82[+-] 0.10(stat.)[+-] 0.08(syst.)(preliminary).
The authors report results on two physics topics from the SLD experiment at the SLAC Linear Collider, using the full sample of 550,000 events of the type ee --> Z° -->q anti-q. The electron beam was polarized, enabled the quark and antiquark hemispheres to be tagged in each event. One physics topics topic is the first study of rapidities signed such that positive rapidity is along the quark rather than antiquark direction. Distributions of ordered in signed rapidity between pairs of particles are analyzed, providing the first direct observation of baryon number ordering along the q anti-q axis. The other topic is the first direct measurement of A{sub s}, the parity-violating coupling of the Z° to strange quarks, by measuring the left-right forward-backward production asymmetry in polar angle of the tagged s quark. They obtain A{sub s} = 0.895 " 0.066(stat.) " 0.062(syst.), which is consistent with the Standard Model and is currently the most precise measurement of this quantity.
We have measured the differential cross sections for the production of[pi][sup+], K[sup+], K[sup 0], K*[sup 0], [phi], p, [Lambda] and their corresponding antiparticles in separate samples of flavor-tagged Z[sup 0][yields] light-flavor (u[bar u], d[bar d], or s[bar s]), Z[sup 0][yields] b[bar b] events. Clear flavor dependences are observed, and the results are compared with the predictions of three fragmentation models. We have also performed a direct measurement of A[sub s], the parity-violating coupling of the Z[sup 0] to strange quarks, by measuring the left-right-forward-backward production asymmetry in polar angle of the tagged s quark. Our preliminary result is A[sub s]= 0.82[+-] 0.10(stat.)[+-] 0.07(syst.).
We have measured the differential cross sections for the production of [pi], K, K°, K*°, [phi], p, [Lambda] and their corresponding antiparticles in separate samples of flavor-tagged Z° 2!light-flavor (u{bar u}, d{bar d}, or s{bar s}), Z° 2!b{bar b} events. Clear flavor dependences are observed, and the results are compared with the predictions of three fragmentation models. We have also performed a direct measurement of A{sub s}, the parity-violating coupling of the Z° to strange quarks, by measuring the left-right-forward-backward production asymmetry in polar angle of the tagged s quark. Our preliminary result is A{sub s} = 0.82 ± 0.10(stat.) ± 0.07(syst.).
The authors have measured the differential cross sections for the production of[pi][sup[+-]], K[sup[+-]], K[sup 0], K*(892), [phi](1,020), p and[Lambda] in hadronic Z[sup 0] decays and in subsets of flavor-tagged Z[sup 0][yields] light quark (u[anti u], d[anti d], or s[anti s]), Z[sup 0][yields] c[anti c] and Z[sup 0][yields] b[anti b] events. Charged hadrons were identified with the SLD Cherenkov ring imaging detector. The vertex detector was employed to select flavor enriched samples and the polarized electron beam from SLC was used to tag quark and anti-quark jets. The authors observe a flavor dependence in the hadron fragmentation functions. The authors present evidence for leading particle production in hadronic decays of the Z[sup 0] boson to light-flavor jets and a direct measurement of the strangeness suppression factor[gamma][sub s].
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.
The authors have measured the differential cross sections for the production of [pi]{sup {+-}}, K{sup {+-}}, K°, K*(892), [phi](1,020), p and [Lambda] in hadronic Z° decays and in subsets of flavor-tagged Z° → light quark (u{anti u}, d{anti d}, or s{anti s}), Z° → c{anti c} and Z° → b{anti b} events. Charged hadrons were identified with the SLD Cherenkov ring imaging detector. The vertex detector was employed to select flavor enriched samples and the polarized electron beam from SLC was used to tag quark and anti-quark jets. The authors observe a flavor dependence in the hadron fragmentation functions. The authors present evidence for leading particle production in hadronic decays of the Z° boson to light-flavor jets and a direct measurement of the strangeness suppression factor [gamma]{sub s}.
Fragmentation is the process by which quarks and gluons organize themselves into hadrons. The fragmentation properties of the bottom quark cannot be predicted from fundamental principles and hence must be determined empirically. We investigate one such property, namely the flavour dependence of the fragmentation process for bottom quarks produced in 1.8-TeV proton-antiproton collisions. This flavour dependence is investigated by determining the 'B'-hadron production ratios. We use a sample of pp data corresponding to an integrated luminosity of 110 pb-1 and reconstruct the following semileptonic 'B'-hadron decays into electrons and charmed hadrons: B+[right arrow]e+neD 0X,hsp sp="0.265"B0[right arrow]e+n eD*-X , B0[right arrow]e+neD- X,hsp sp="0.265"B0s[right arrow]e +neD-s X and L0b [right arrow]e+neL- cX . With these data, we measure the ratios of fragmentation fractions fd/fuvmk id="vm1"=88± 21%, fs/fu+fdvmkr rid="vm1"= 21.5±7.1%hsp sp="0.265"and fbaryon/fu+fd vmkr rid="vm1"=12.0±4.2%. Assuming that these four hadrons saturate production of weakly-decaying ' B' hadrons, that is, that fu+fd+fs+fbaryon 1 , we determine fuvmk id="vm1"=39.8±5.4 %, fdvmkr rid="vm1"=35.2±4.8 %, fsvmkr rid="vm1"=16.1±4.5 %hsp sp="0.265"and fbaryonvmkr rid="vm1"=9.0± 2.9%. These results represent the first measurement of all four 'b'-quark fragmentation fractions in a single experiment. These fractions are in agreement both with previous phenomenological interpretations and with other experimental measurements.
We present a measurement of the {ital b} quark fragmentation function from a sample of semi-leptonic {bold B} decays collected between 1993 and 1995 in the SLD experiment at SLAC. The energy of each tagged {bold B} hadron was reconstructed using information from the lepton and a partially reconstructed charm decay vertex. A comparison of the scaled energy distribution with several phenomenological models of heavy quark fragmentation was made, using the same model in each case to correct the data. The average scaled energy was found to be {l_angle}[chi]{sub E}{r_angle} = 0.697±0.012({ital stat}){sup +0. 028}{sub -0.024} ({ital syst})(preliminary).