Measurements of the cross section for the production of electron pairs with invariant masses between 4 and 8.7 GeV are presented as a function of the centre-of-mass energy ( s = 28 to s = 62 GeV ) of the colliding proton beams. A significant excess of events is observed in the region 8.7 to 10.3 GeV; these are ascribed to the ϒ(9.5 GeV) resonances and estimates of the production cross sections are given.
Axis error includes +- 40/40 contribution (Due to the uncertainty in efficiency).
Axis error includes +- 40/40 contribution (Due to the uncertainty in efficiency).
The inclusive production of resonances is systematically studied in K + p interactions at 32 GeV/ c . Total production cross sections are given for three baryon resonances, five vector and three 2 + tensor mesons. We also compare the central and fragmentation components of the total production cross sections with quark model predictions.
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We observe a K−π+ state at 1786 ± 8 MeV with a width 95 ± 31 MeV in the reaction K−p→K−π+n at 6 GeV/c, from an experiment carried out at the Brookhaven National Laboratory multiparticle spectrometer.
ERROR INCLUDES SYSTEMATIC NORMALIZATION UNCERTAINTY.
We report results from a measurement of the inclusive processes pp→Xp and pd→Xd in the range 5<Mx2s<0.1, 0.01≲|t|≲0.1 (GeV/c)2, and incident proton momenta of 65, 154, and 372 GeV/c. Both pp and pd data show an exponential t dependence and a dominant 1Mx2 behavior for Mx2s≲0.05. By comparing pp and pd data we test factorization and, using the Glauber model, we measure the XN total cross section, σXN=43±10 mb.
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As a part of the study of the inclusive production of electron pairs in pp collisions at the CERN Intersecting Storage Rings (ISR), a search has been performed for additional photons accompanying J/ψ particles. The results suggest that (43±21)% of the J/ψ's are produced via the photonic decay of one of the χ(3.5) states.
The cross section times branching ratio.
The invariant mass spectrum of neutral final states produced in π − p charge-exchange scattering at 40 GeV/ c has been studied, searching for heavy particles decaying in 2γ. A peak is observed around 2.85 GeV/ c 2 . The cross section of the reaction π − p→X(2.85)+n, times the branching ratio of the X→2 γ decay, is measured to be σ × BR ⋍ 2 × 10 −34 cm 2 .
MEAN VALUE OF -T = 0.28 +- 0.04 GEV**2.
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A clear, prompt dimuon signal has been observed in a low-statistics streamer-chamber experiment with 16-GeV/c πp interactions. The good mass resolution makes it possible to identify the contributions from ρ and ω decays and η and ω Dalitz decays. An excess of events is observed in the mass region ∼400-600 MeV which is not accounted for by the above-mentioned decays.
The data with PI+- beam obtained from the combination of PI+ and PI- beams.
Electroproduction of hadrons is studied in the kinematic region W < 2.8 GeV and 0.3 < Q 2 < 1.4 GeV 2 using the DESY streamer chamber. Prong cross sections, charged-particle multiplicities and inclusive π − distributions are presented. The average charged multiplicity is found to be independent of Q 2 in the Q 2 range studied here; however it is lower than in photoproduction. The fraction of forward π − is found to be significantly less in electroproduction than in photoproduction. The 〈 p ⊥ 2 〉 for inclusive π − is, for all x values, similar to that found in photoproduction.
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The vector meson production, hypercharge exchange reactions K − p → ( φ , ω , ϱ ) Λ and ( φ , ϱ ) Σ 0 are studied at 4.2 GeV/ c incident momentum. The data come from a high statistics bubble chamber experiment with a sensitivity of ∼ 120 events/μb. Total and differential cross sections are presented. The vector meson density matrix elements and hyperon polarization are investigated as functions of momentum transfer. Amplitude analyses are performed for all five reactions. The results are compared with duality and quark model predictions, as well as used to test current ideas in two-body phenomenology.
ERRORS INCLUDE THE 5 PCT MODEL ERROR BUT NOT THEORETICAL RESONANCE PARAMETRIZATION ERRORS.
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