An experimental study of b-quark jets using high- p T electrons was carried out at √ s =58 GeV with the TOPAZ detector at the e + e − collider TRISTAN at KEK. The forward-backward charge asymmetry of the b-quark was obtained to be A b b ̄ =−0.55±0.27( stat. )±0.07( syst. ) , consistent with the standard model prediction. Also, such jet properties of the b-quark as the average charged multiplicity and the rapidity of charged particles were analyzed. In order to purify the b-quark event samples in this analysis, only events with backward-going electrons or forward-going positrons were used. The energy dependence of these jet properties was studied by making comparisons with the results of the DELCO experiment at the PEP collider (√ s =29 GeV) at SLAC.
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Mean values of jet properties for b-jet sample.
We have used the Fermilab 30-in. bubble-chamber-hybrid spectrometer to study neutral-strange-particle production in the interactions of 200-GeV/c protons and π+ and K+ mesons with nuclei of gold, silver, and magnesium. Average multiplicities and inclusive cross sections for K0 and Λ are measured, and a power law is found to give a good description of their A dependence. The exponent characterizing the A dependence is consistent with being the same for K0 and Λ production, and also the same for proton and π+ beams. Average K0 and Λ multiplicities, as well as their ratio, have been measured as functions of the numbers of projectile collisions νp and secondary collisions νs in the nucleus, and indicate that rescattering contributes significantly to enhancement of Λ production but not to K0 production. The properties of events with multiple K0's or Λ's also corroborate this conclusion. K0 rapidities are in the central region and decrease gently with increasing νp, while Λ rapidities are in the target-fragmentation region and are independent of νp. K0 and Λ multiplicities increase with the rapidity loss of the projectile, but their rapidities do not.
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We present the charged-particle multiplicity distributions for e+e− annihilation at center-of-mass energies from 50 to 61.4 GeV. The results are based on a data sample corresponding to a total integrated luminosity of 30 pb−1 obtained with the AMY detector at the KEK storage ring TRISTAN. The charged-particle multiplicity distributions deviate significantly from the modified Poisson and pair Poisson distributions, but follow Koba-Nielsen-Olesen scaling and are well reproduced by the LUND parton-shower model.
Fully corrected charged particle multiplicity distributions. Errors for n=2 and 4 are systematic only since these were derived using the LUND 6.3 Monte Carlo normalized to the observations at higher n values.
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The production rate of charged D* mesons in jets has been measured in 1.8-TeV p¯p collisions at the Fermilab Tevatron with the Collider Detector at Fermilab. In a sample of approximately 32 300 jets with a mean transverse energy of 47 GeV obtained from an exposure of 21.1 nb−1, a signal corresponding to 25.0±7.5(stat)±2.0(syst) D*±→K∓π±π± events is seen above background. This corresponds to a ratio N(D*++D*−)/N(jet) =0.10±0.03±0.03 for D* mesons with fractional momentum z greater than 0.1.
Mean jet transverse energy is 47 GeV. Branching rates for D* --> D0 PI of 0.57 +- 0.04 (DSYS=0.04) and D0 --> K- PI+ of 0.042 +- 0.004 (DSYS=0.004), from MARK-III have been used.
We have used the Fermilab 30-in. bubble-chamber hybrid spectrometer to study multiparticle production in the interactions of 200-GeV/c protons and π+ and K+ mesons with nuclei of gold, silver, and magnesium. We find that the multiplicities of produced particles and negative particles increase linearly with the number of projectile collisions, with no beam or target dependence. The number of secondary collisions in the nucleus increases significantly less rapidly with the number of projectile collisions than has been reported by a streamer chamber experiment. The properties of secondary collisions suggest that they arise from rescattering of recoil nucleons rather than intranuclear cascade of produced particles. Dispersions of multiplicity distributions at fixed impact parameter are in better agreement with a model of independent sources than with Koba-Nielsen-Olesen scaling.
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PION means all charged secondaries except identified protons.
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We report on the interactions of an incident 200 GeV / c beam composed of 33% protons, 16% kaons, and 48% pions on targets of silver and gold mounted in the Fermilab 30″ bubble chamber. Within our limited statistics, we find the total cross sections and average multiplicities to agree with previously published data. We find the KNO scaling distribution curve to be broader for heavy nuclei than for hydrogen. We present the first data for V 0 production on gold and silver. We also present, for the first time, evidence for a positive charge excess among the sample of relativistic tracks from interactions on gold and silver. We observe a trend where the positive charge excess increases with target atomic number and with increasing charged particle multiplicity. We find the charge excess to exist among the sample of particles having greater than 2 GeV / c momentum and to persist in the sample with momentum greater than 4 GeV / c .
SIG REFERS PRODUCTION OF 2 OR MORE CHARGED PARTICLES EXCLUDING ELASTICS BUT INCLUDING COHERENT PRODUCTION. MULT REFERS TO RELATIVISTIC SECONDARIES (BETA > 0.7).
NO CORRECTION FOR GAMMA CONVERSIONS IN THE TARGET IN THIS TABLE BUT DIFFERENCE DOES NOT NEED CORRECTION.
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The inclusive and semi-inclusive cross sections for K*±(890) and Σ±(1385) resonances are determined in p¯p interactions at 14.75 GeV/c. They account for a large fraction of the KS0 and Λ0 produced. The K*-resonance production also affects the low-pT2 distribution of inclusive KS0. The x distributions of the resonance production are studied in terms of a simple quark-recombination model.
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