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New data on the ν ′ ν system produced in the π − p charge exchange at 38 GeV c momentum confirm the existence of the narrow ν ′ ν resonance X(1910). The hypothesis of the X(1910) quantum numbers being a J PC = 1 −+ , forbidden for the q[ovbar|q] meson, is proposed to explain the extremely low limits obtained for X(1910) decays through π 0 π 0 , νν and K 0 s K 0 s channels and the flat t -dependence of the X(1910) production cross section.
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Evidence for a new meson decaying into ηη′ has been found in 38 GeV π − p charge-exchange interactions. The mass and the width of this meson are (1917 ± 15) MeV and (90 −50 +35 ) MeV, respectively. Possible spin and parity assignments are J PC = 0 ++ , 1 −+ or 2 ++ , isospin and G -parity are I G = 0 + . The t -dependence of the differential cross section follows an exponential behaviour exp( bt with a small slope: b = (2±1) (GeV/ c ) −2 .Upper limits on its decay into ππ, ηη and K K exotic interpretation of this meson.
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The π − p→ ωω n reaction has studied for the first time at the 70 GeV IHEP accelerator. The six photons from the decay of the two ω mesons were detected in GAMS-2000, a hodoscope multi-photon spectometer. Two resonances decaying into ωω,X (1640) and X(1960), have been observed. Their quantum numbers are J PC =2 ++ , I G =0 + . The reaction is dominated by the one-pion exchange mechanism. The production cross sections σ. BR(X→ ωω ) are 0.65±0.15 μ b and 1.0±0.2 μ b, respectively.
X(1640) IS A JPC - 2++, IG - 0+ MESON WITH MASS 1643+-7 MEV.
X(1960) IS A JPC - 2++, IG - 0+ MESON WITH MASS 1956+-20 MEV.
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A narrow meson which decays into ηη is observed in 38 GeV/ c π − p collisions at large momentum transfer. The experiment has been performed at the Serpukhov accelerator with the GAMS-2000 spectrometer. The mass of this new meson is (1755 ± 8) MeV, its width is less than 50 MeV. Its spin-parity is J PC =0 ++ or less probably 2 ++ .
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A structure has been observed at 2220 MeV in the mass spectrum of ηη ′ systems produced by 38GeV/ c and 100 GeV/ c ′ negative pions on protons. The angular distribution of the decay products shows that this structure is presumably a spin J ⩾ 2 meson.
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Results are presented from experiment WA7 at the CERN SPS, which has measured the elastic differential cross sections of π ± p, K ± p, p p and pp at incident momen ta of 20, 30 and 50 GeV/ c . The measurements cover the momentum transfer range 0.5 < | t | < 8 (GeV/ c ) 2 , corresponding to c.m. scattering angles between 10° and 50°. The experimental set-up, trigger logic and data analysis are described. The experimental results are compared with existing meson-proton and nucleon-proton data at lower and higher energies covering the medium- and large-| t | region. Some prominent models and their predictions for elastic scattering at WA7 energies and beyond are reviewed, with emphasis on geometrical scaling, factorizing eikonal models, lowest-order QCD and other dynamical exchange-type models. Results for p p two-body annihilation into π − π + and K − K + at 30 and 50 GeV/ c , obtained in parallel with the elastic p p data, are also presented.
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We present the first results on the production of fast (p>10 GeV/c)p,\(\bar p\), Λ and\(\bar \Lambda \) from π± hydrogen and nucleus interactions at 30 GeV/c using the CERN Ω′ spectrometer. We have used five nuclear targets (C, Al, Cu, Sn, Pb) to study theA-dependence of the inclusive particle distributions in the region 0.3<xF<0.6. The high statistical level of our experiment allows us to demonstrate the differentA-behaviour of baryon and antibaryon inclusive reactions. We relate this difference to the final state interaction inside a nucleus using the formation-zone model.
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