We present results on inclusive φ meson production in K + p interactions at 70 GeV/ c in the kaon fragmentation x >0.2 region. Comparison with other data on φ meson production in K ± and p induced reactions provides evidence that the strange valence-quark fragmentation or recombination processes play the dominant role in the K ± → φ transitions. Arguments are presented that the kaon valence strange s -quark carries a much higher momentum fraction than the u-quark. Evidence for the previously observed narrow φπ + state at mass ∼2.1 GeV is discussed.
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We present results on the inclusive polarization of Λ hyperons produced in K + p interactions at 32 and 70 GeV/ c . A large positive Λ polarization is observed in the kaon fragmentation region. The polarization is energy independent, increases strongly with increasing x , but shows essentially no p T -dependence.
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Results are presented on the inclusive production of π± mesons and protons in\(\bar p\)p interactions at an incident antiproton momentum of 32 GeV/c in the MIRABELLE bubble chamber, based on a sample of 55,000 inelastic events. The spectra of π+(π−) andp(\(\bar p\)) are separated in the whole kinematically admitted region of phase space by a statistical method. The semi-inclusive and inclusive cross sections and the main average characteristics of π andp production are calculated. The invariant differential cross sections are studied as functions of the Fevnman scaling variablex, the rapidity and the transverse momentum. Thex distribution of π± mesons in the proton fragmentation region does not show any significant contribution from quark exchange or annihilation processes. A possible contribution of hard quark scattering on mesons or baryons is observed for large transverse momenta.
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Total and differential cross sections ofK*−(890),K*−(890),\(\bar K^{ * 0} \)(890),K*0(890),\(\bar K^{ * 0} \)(1430) andϱ0(770) produced inK−p interactions at 110 GeV/c are presented. The cross sections of the neutral resonances show a smooth increase with energy from 10 to 110 GeV/c incident momentum. For theK*+(890) and theK*0(890), i.e. the resonances with strangenessS=+1, this rise is quite significant: their cross sections practically double between 32 GeV/c and 110 GeV/c incidentK− momentum. About 50% of the neutral kaons and 30% of charged pions produced inK−p interactions at our energy are found to be decay products of the resonances considered.
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Results are presented on the inclusive photoproduction of λ and λ for incident photon energies between 25 and 70 GeV. The slope parameter of the p T 2 distribution is found to be 2.83±0.1 GeV −2 for λ and 3.28±0.25 GeV −2 for λ . The x F distributions, measured in the range −0.2 to 0.7, show that while λ are produced centrally, λ production extends to more negative values of x F ; the shapes show no energy dependence and are similar to those in pion-induced reactions. The polarization of the produced λ is less than 10%. The results are discussed in terms of vector dominance and quark fusion models.
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Prompt dimuon production has been measured. Events with mass up to 25 GeV/c2 are observed, as well as the J and ϒ resonances. Cross sections are given for J and ϒ production. For the continuum, the scaling function F(τ) is measured at very small values of τ=ms covering the range 0.05<τ<0.20.
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HERE UPSILON = ALL USILON FAMILY. ANGULAR DISTBN. IS SEEN TO BE ISOTROPIC.
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We present data on dimuon production by 16 GeV π + and π − beams on a Cu target. From the data we evaluate, for π − N collisions, the fraction of dimuon events that originate from the annihilation process q q ̄ → μ + μ − . Using this information the experimentally determined cross section for the process q q ̄ → μ + μ − is observed to be in agreement with the Drell-Yan model over a wide range of incident energies. The observed deviations from exact scaling are of the order predicted by QCD calculations for the Q 2 -dependence of the nucleon and the pion structure function.
CROSS SECTIONS ARE PER COPPER NUCLEUS.
CROSS SECTIONS ARE PER COPPER NUCLEUS.
The inclusive production of Λ , K S 0 , Σ ± (1385) and K ∗± (892) in π − p interactions at 6 GeV/ c has been studied. The observed cross sections are: σ ( Λ )=0.94±0.06 mb, σ (K S 0 )=0.98±0.06 mb, σ ( Σ + (1385))=60±7 μb , σ ( Σ − (1385))=90±9 μ b, σ( K ∗+ (892))=216±28 μ b and σ( K ∗− (892))=41±8 μ b , respectively. The inclusive spectra of these particles are presented as functions of squared transverse momentum and Feynman scaling variable x . The polarization of Λ has also been investigated. It is found from a comparison with higher-energy data that the inclusive cross sections for Σ ± (1385) and the production ratios Σ ± (1385)/ Λ in π − p at 6 GeV/ c have not reached the high-energy limiting values.
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In a large-acceptance spectrometer, muon pairs and associated hadrons were observed with μμ masses up to 10 GeV/ c 2 and ΔM M = 0.015 resolution. We report here on the production of 4000 J/ ψ and 80 ψ ′ mesons.
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