S. Iwata

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

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 A model incorporating K ∗ resonance contributions and simple backgrounds is shown to quantitatively reproduce the mass dependence of the partial wave amplitudes governing the production and decay of the K 0 π + π − system. A fit of this model to these amplitudes confirms the resonance interpretations of the well-established 1 + K 1 (1400), the 2 + K 2 ∗ (1430), the 3 − K 3 ∗ (1780), and the less well-known 1 − states, the K ∗ (1410) and the K ∗ (1790). The 4 + amplitudes are shown to be consistent with the production and decay of the 4 + K 4 ∗ (2060). A second 2 + enhancement at a mass of ∼ 1.95 GeV/ c 2 can be interpreted as resonant and may be the radial excitation of the K 2 ∗ (1430) or the triplet partner of the K 4 ∗ (2060). New measurements of the masses, widths and branching ratios of these states are given, and the implications of these data for the spectroscopy of the non-strange meson sector are discussed.

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 Strange Meson Resonances Observed in the Reaction

Preliminary results are presented from an analysis of the π+π− system produced in the reaction K−p → π+π−Λ at 11 GeV/c observed with the LASS spectrometer at SLAC. A clear ϱ - ω interference effect is observed, and a fit to the natural parity exchange mass distribution yields a branching fraction estimate of (1.7 ± 0.5) % for the decay ω → π+π−. An amplitude analysis reveals that the bump in the mass distribution in the vicinity of the ƒ2(1270) actually contains a significant P-wave component. The mass dependence of the corresponding amplitude and phase is well described by a resonant Breit-Wigner line-shape with mass (1266 ± 14) MeV/c2, width (166 ± 35) MeV/c2, and estimated elasticity ∼ 5%. The interpretation of this state as the first radial excitation of the ϱ(770) is discussed.

K^- p \to \bar{K}0 \pi^+ \pi^- n

The correlation between a high transverse momentum π0and η and a second π0 have been measured using an apparatus with large azimuthal acceptance. The angular distribution of α, measuring the deviation from collinearity in azimuth, peaks near zero. The r.m.s. of the distribution is found to have an inverse logarithmic rather than a 1p fall-off.