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The cross section for photoproduction of π0 mesons was measured at a photon energy of 3 GeV and squared four-momentum transfer (t) of -0.1 to -1.2 (GeV/c)2 using plane-polarized photons. The asymmetry was found to be consistent with +1.0 for t values above -0.4 and below -1.1. For −0.4<~t<~−1.0 there is a dip in the asymmetry and at t=−0.6 it drops to 0.55 ± 0.15. This result precludes a simple Regge model with ω0 and B; a theoretical description requires Regge cuts or an ω′ exchange.
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MIT PREP (1967).
We present results for the differential cross sections of neutrinos and antineutrinos on nucleons in the energy range E = 2−200 GeV, from the BEBC and Gargamelle experiments. The structure functions F 2 , 2 χF 1 and χF 3 have been evaluated as a function of χ and q 2 . Deviations are observed from Bjorken scaling, which are very similar to those found in electron and muon inelastic scattering. For the Callan-Gross ratio, we find 2χF 1 F 2 = 0.80 ± 0.12 and the corresponding value for 〈R〉 = 〈 σ S σ T 〉 = 0.15 ± 0.10 . Our results are consistent with the Gross-Llewellyn-Smith sum rule; we measure ⩾2.5 ± 0.5 valence quarks per nucleon. Quark and antiquark distributions are given. The Nachtmann moments of F 2 and χF 3 are quantitatively consistent with the predictions from QCD. The value of the strong interaction parameter is λ = 0.74 ± 0.05 GeV without corrections, and 0.66 ± 0.05 GeV including α S 2 corrections. The moments of the gluon distribution are found to be positive and indicate an χ distribution of gluons which is comparable with that of the valence quarks.
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We have measured the inclusive cross-section for π0 production at large transverse momentum by 200 GeV/c positive and negative hadron beams on Carbon targets (2.9<PT<6 GeV/c; −0.4<y*<1.2). We used the NA3 spectrometer at the CERNSPS.
CONVERSION TRIGGER SELECTION.
CALORIMETER TRIGGER SELECTION.
This paper presents results of an experiment on hadron production in deep-inelastic electron scattering. Good agreement with the predictions of the quark-parton model is found. The Fragmentation functions for u and d quarks into pions are determined, and comparison is made with other deep-inelastic processes and with recent quark jet parametrizations.
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Data on muon-pair production by pions are used to determine the momentum distribution for valence quarks in the pion. The shape of a nucleon structure function is also obtained and is compared with a calculation based on existing data.
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Data from a study of muon pairs produced in hadron-nucleus collisions are compared with the Drell-Yan model. Comparison of dimuon production by π+ and π− mesons on an isoscalar target shows evidence for a charge asymmetry characteristic of an isospin-nonconserving electromagnetic process. The average transverse momentum of the pairs increases smoothly with pair mass. Data taken on carbon and tin targets are used to extract the dependence on target atomic weight.
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We present results of a large-acceptance experiment in which muon pairs were observed in the mass range 0.6 to 6.0 GeV/c2. Emphasis is given to features of the production of Jψ and ψ′(3.7) particles. We find [Bσ]ψ′(3.7)[Bσ]Jψ to be 0.007±0.004 for p-C and 0.018±0.007 for π+-C interactions. Comparison with results from e+e− storage rings indicates that both the Jψ and the ψ′(3.7) are produced strongly rather than electromagnetically in our experiment.
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We present the results of a study of muon pairs with invariant masses greater than 4.05 GeV/c2 produced in high-energy pion-nucleon interactions. The production cross section together with the inferred pion and nucleon structure functions are reported and compared with other experiments and with QCD predictions. The transverse-momentum distributions are also presented. Finally, the full angular distribution in cosθ and φ is given as a function of mass, Feynman x, and transverse momentum. Longitudinal photon polarization is seen in the lower portion of the mass range at high xπ. This result is compared with a higher-twist model.
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For the reaction π−N→V0X, where V0 is a Ks0, Λ, and Λ¯ and X are charged particles, we measured the transverse- and longitudinal-momentum distributions, and inclusive cross sections for the V0 and for K*±(892), Σ±(1385), and Ξ±(1321). We compare our results with predictions of quark-counting rules, and conclude that valence quarks play an important role in strange-particle production.
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