J.P. Lagnaux

Evidence for a 1-+ exotic meson

Abstract A non q q ,J PC = 1 −+ , I G =1 − meson has been observed in the study of the exclusive reaction π − p→π 0 ηn at 100 GeV. Its mass is (1406±20) MeV. Its width is (180±30) MeV.

Scattering of Negative Pions on Helium

Abstract Differential cross sections for negative pion scattering on 4 He have been measured at five pion kinetic energies between 110 and 260 MeV in the angular range from 5° to 180°. Total cross sections have also been measured at eleven energies between 67 and 285 MeV. The differential cross sections have been fitted with a phenomenological expression for the nuclear scattering amplitude. Conventional phase shifts have been reconstructed starting from the parameters of the fits.

ELASTIC SCATTERING OF POSITIVE KAONS ON POLARIZED PROTONS BETWEEN 0.87 AND 2.74 GeV/c. RESULTS AND PHASE-SHIFT ANALYSIS.

Abstract Polarization and differential cross-section data at 16 momenta between 0.86 and 2.74 GeV/ c are presented. (Preliminary data on some of the momenta have been published earlier.) In an energy-independent phase-shift analysis from threshold up to 2.5 GeV/ c , resonant-like as well as non-resonant solutions are found for the P 3 wave. An helicity flip-non-flip decomposition of the partial waves partly supports the indications found in the analyses of other reactions that the pomeron is built up mainly from s -channel helicity non-flip contributions.

Production of G(1590) in 300 GeV central

Abstract Significant production of G(1590), a scalar glueball candidate, is observed in a study of η pairs produced in π−N central collisions at 300 GeV/ c .

\pi^-

Abstract Polarization and differential cross section data for elastic proton-proton scattering between 0.86 and 2.74 GeV/ c are presented. A comparison is made with existing phase-shift analyses.

N collisions

Summaryη′η pair production in the charge exchange reaction π−p→η′ηn has been observed and studied in a search for glueballs with the 38 GeV/c pion beam of the 70 GeV IHEP accelerator. The γ-rays from the decay η′η→4γ were detected with the hodoscope spectrometer GAMS-2000. The η′η events in the mass range from threshold up to 1.8 GeV are decays of the scalar G(1590)-meson which has been already observed in its ηη decay mode. The measured ratio of the partial widths of the G→η′η and the G → ηη decay channels is 2.7±0.8 in agreement with the value expected for glueballs.RiassuntoÈ stata osservata e studiata la produzione di coppie η′η nella reazione di scambio di carica π−p→η′ηn nella ricerca di sfere di gluoni con il fascio di pioni a 38 GeV/c dell’acceleratore IHEP a 70 GeV. I raggi gamma derivanti dal decadimento η′η→4γ sono stati rivelati con lo spettrometro odoscopico GAMS-2000. Gli eventi η′η nell’intervallo di massa dalla soglia fino a 1.8 GeV sono decadimenti del mesone scalare G(1590) che è stato già osservato nel suo modo di decadimento ηη. Il rapporto misurato delle ampiezze parziali dei canadi di decadimento G→η′η e G→ηη è 2.7 ± 0.8 in accordo con il valore atteso per le sfere di gluoni.РезумеНаблюдается и исследуется рождение η′η пар в реакции перезарядки π−p→η′ηn с целью поиска «глюболов», используя пионный пучок с импульсом 38 ГэB/c ускорителя 70 ГэB IHEP. γ-лучи из распада η′η→→4γ детектируются с помощью спектрометра GAMS-2000. η′η события в области масс от порога вплоть до 1.8 ГэB представляют распады скалярного G(1590)-мезона, который уже наблюдался в моде распада ηη. Измеренное отношение парциальных ширин каналов распадов G→η′η и G → ηη, составляет 2.8±0.8, что согласуется с ожидаемой величиной для «глюбола».

Polarization in elastic proton-proton scattering between 0.86 and 2.74 GeV/c

Abstract 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.

Study of

The partial widths of the η′(958) decays into 2γ, ωγ, 3π0 andηπ0π0 have been measured with the GAMS-2000 spectrometer at the 70 GeV IHEP accelerator. Upper limits for the η′ decays into 3γ, π0γγ, 2π0 and 4π0 have also been obtained. The slope of a linear matrix element for theG-parity violating decayη′→3π0 has been determined.

\pi^- p \to \eta^\prime \eta n

Abstract Polarizationdata for the reaction pp → π+d on polarized protons at 1.04, 1.13, 1.21, 1.37 and 1.45 GeV/c are presented. The coefficient characterizing the angular distribution of the polarization show an energy dependence similar to that of the total cross-section and are consistent with the view that N∗ ( 3 2 , 3 2 ) production dominates the reaction mechanism.

in a Search for Glueballs

Abstract Polarization and differential cross-section data are presented for elastic scattering of antiprotons on polarized protons at eight momenta between 0.9 and 2.5 GeV/ c . The data are fitted with a diffraction model.