We report measurements at the CERN PS of the production cross section of J/ψ(3.1) by 24 GeV protons on hydrogen, carbon, and tungsten.
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ASSUME B.R.(E+E-) =0.069.
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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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We present the results of a detailed study of ω′(1675) production in the reaction π+p→Δ++π+π−π0 from a high-statistics bubble-chamber experiment at 15 GeV/c. We have measured the mass, width, and cross section as well as differential cross section and spin density matrix elements and compare then to A20 production in the same reaction. We show clear evidence for the resonant phase increase of the 3− (ρπ)fI=0 amplitude with ω′(1675) production.
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NOTE THAT THE SCALES FOR THE DIFFERENTIAL CROSS SECTION ARE WRONG IN THE PUBLISHED FIGURE.
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We have measured the charge-exchange reaction pp → (p π + ) (p π − ) at s = 23, 31, 45, 53, and 63 GeV at the ISR, using the Split Field Magnet detector. The data are characterized by a sharp forward peak of width 0.02 (GeV/ c ) 2 , followed by a much gentler slope at higher | t |; sizeable Δ ++ , Δ 0 , and N 0 production is observed in the (Nπ) mass spectra. Two different components are present in the data following power-law energy dependence of the type p lab − n with n 1 = −1.63 ± 0.13 and n 2 = −0.96 ± 0.07, respectively, indicating the onset of mechanisms in competition with pion exchange at ISR energies.
CHARGE EXCHANGE DOUBLE DIFFRACTION DISSOCIATION OF PROTONS. DEL++, DEL0, N(1520)0 AND N(1688)0 RESONANCES IDENTIFIED IN PROTON-PION MASS SPECTRA.
We report results on a new measurement of the double diffractive reaction pp → (p π + π − ) (p π + π − ) at the ISR obtained with the Split Field Magnet detector. Experimental procedures and data analysis are discussed in detail. The cross section measured at the five standard ISR energies exhibits an increase of (55 ± 7)% in the s -range from 549 to 3892 GeV 2 .
DOUBLE DIFFRACTION DISSOCIATION OF PROTONS.
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FOR THE FPRIME A PURE 2+ STATE IS ASSUMED AND ONLY JZ=+1,0,-1 CONTRIBUTIONS ARE CONSIDERED.
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We present results from an experiment studying the production of single particles and jets (groups of particles) with high p ⊥ (transverse momentum) in 200 GeV/ c interactions on a beryllium target. We give a detailed discussion of the ambiguities in the jet definition. The jet and single-particle cross sections have a similar shape but the jet cross section is over two orders of magnitude larger. The events show evidence for the coplanar structure suggested by constituent models, and the momentum distributions of charged particles give strong support to a simple quark-quark scattering model.
NOMINAL CALORIMETER THRESHOLD WAS 3 GEV/C. AT WHICH PT TRIGGER EFFICIENCY SHOULD BE 50 PCT. THIS DATA HAS AN ADDITIONAL 20 PCT. NORMALISATION ERROR.
THIS TABLE REFERS TO JET WITH THRESHOLD OF 3 GEV/C. THE JET PONTS ARE AVERAGED OVER ROUGHLY EQUAL AMOUNTS OF +VE AND -VE BEAMS.
THIS TABLE REFERS TO JET WITH THRESHOLD OF 4 GEV/C. THE JET PONTS ARE AVERAGED OVER ROUGHLY EQUAL AMOUNTS OF +VE AND -VE BEAMS.
We report on the analysis of inclusive neutral current events produced in neutrino and antineutrino narrow band beams. We find for incident neutrino energies in the range 12–200 GeV and for hadron energies above 12 GeV a neutral to charged current cross-section ratio of R v = 0.293 ± 0.010 for incident neutrinos, and R v = 0.35 ± 0.03 for antineutrinos. These ratios are consistent with the Weinberg-Salam model, with sin 2 θ w = 0.24 ± 0.02.
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The charged-current cross sections for neutrinos and antineutrinos on nucleons in the energy range 20–200 GeV are given. Taken in conjunction with the previous Gargamelle results, they show that σ E is almost constant with energy for antineutrinos, and falls with energy for neutrinos. The value of 〈q 2 〉 E decreases with energy for both neutrinos and antineutrinos, and these deviations from exact Bjorken scaling are consistent with those observed in electron and muon inelastic scattering. We find no evidence for new heavy quark states with right-handed coupling.
Measured charged current total cross section.
Measured charged current total cross section.