M. Goldberg

Characteristics of J/ψ and ϒ production at the CERN intersecting storage rings

We present the B(dθdy)y=0 for J/ψ over thefull range of ISR energies and for ϒ at √s = 53 and 63 GeV, using their dielectron decay mode. The average transverse momentum and the decay angles are presented. We found (pT) = 1.75 ± 0.19 GeV for ϒ, being higher than (pT) of the continuum and rising with √s. We present a comparison of the cross sections of J/ψ and ϒ with those of the continuum, at the same masses, as a function of √s. An appropriate scaling of the hadronic production of quark-antiquark narrow bound states involving ⋉, J/ψ, ψ′, ϒ, and ϒ′ is presented as a function of m/√s at y = 0, and is compared with Drell-Yan scaling.

Inclusive η production at high pT at the ISR

Abstract The inclusive η production cross section at the CERN ISR has been measured for p T values of up to 11 GeV/ c . We find that the η π 0 cross-section ratio has an average value of 0.55 ± 0.07 and varies little with p T .

Study of photons produced simultaneously with the J/ψ particles at the CERN intersecting storage rings

Abstract 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/ψs are produced via the photonic decay of one of the χ(3.5) states.

Study of

Abstract The inclusive production of electron pairs with and without additional photons was measured at the CERN Intersecting Storage Rings (ISR). The investigation of J ψ particles with associated photons indicated that 47 ± 8% of the J ψ were produced via the photonic decay of one of the χ(3.5) states. The upper limit of the production cross-section ratio times the branching ratio into electron pairs of ψ relative to J ψ was found to be 2% at centre-of-mass energy of √=62 GeV

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Abstract Inclusive π 0 production at 90° has been studied at the ISR at s 1 2 = 52.7 and 62.4 GeV over the p T range from 7 to 15 GeV/ c . The two photons from π 0 decay yielded overlapping electromagnetic showers in the liquid-argon-Pb plate calorimeter detector system. Any direct photon production is included in these measurements. For large values of p T , the cross section is observed to decrease with p T more slowly than the p T −8 behaviour which has been observed at lower values of p T .

Production Properties at the {CERN} Intersecting Storage Rings

Abstract 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.

Inclusive π0 production at very large pT at the ISR

Abstract Data from a study of electron pairs produced in pp collisions (√ s = 5 and 63 GeV) are used to extend measurements of the scaling function down to m /√ s ≈ 0.07 (4.5 m The average transverse momentum of dielectrons was found to be 1.43 ± 0.07 GeV, independent of mass (in the range 4.5 m s . The angular decay distribution of the pairs was measured in the s -channel helicity system and found to behave like 1 + α cos 2 θ, where α = 1.15 ± 0.34. The angular decay of ϒ at the same energies was found to have α = 0.31 ± 0.35.

The cross section for the production of massive electron pairs and the ϒ(9.5 GeV) in proton-proton collisions at the CERN ISR

Abstract The cross-section for J/ψ production in proton-proton collisions has been measured as a function of centre-of-mass energy at the CERN Intersecting Storage Rings by observing its decay into electron-positron pairs. This cross-section is found to rise by a factor of about six over the full centre-of-mass energy range from √s=23 to √s=63 GeV. Electrons resulting from this decay were identified by the use of liquid argon calorimeters and lithium foil transition radiators. Measurements of the energies of the electrons were obtained from the liquid argon calorimeters.

Study of massive electron pair production at the CERN intersecting storage rings

Abstract The inclusive production of π 0 at large values of p T in pp collisions at the ISR has been studied. In this experiment the two photons are resolved and separately measured for p T values of up to 6 GeV/ c , giving confidence that the desired signal has been separated from various backgrounds.

The cross-section for J/ψ production in proton-proton collisions at centre-of-mass energies between 23 and 63 GeV

Abstract Correlations of two π 0 mesons with transverse momenta up to 10 GeV/ c have been measured utilizing apparatus with large azimuthal acceptance. The data are analysed in the context of constituent scattering models, and also compared with a simple “back-ground” hypothesis.