The polarization in pion-nucleon charge exchange was measured at 6 GeV/c incident momentum for 0.1 (GeV/c)2 < |t| < 1.6 (GeV/c)2. Using the channel π+ n ↑ → π0p allowed precise measurement of the recoil proton for good rejection of inelastic events. The results are compared with previous experiments using channel π−p ↑ with or without detection of the recoil neutron.
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In an experiment carried out at the CERN Proton Synchrotron and using the CERN polarized deuteron target, the reaction π+n↑→π+π−p has been measured in the region -t=0.1–1.0 (GeV/c)2 and m(π+π−)=0.36–1.04 GeV at incident momenta of 5.98 and 11.85 GeV/c. We present the m and t dependence of the measured 14 linearly independent spin-density-matrix elements and of the bounds on the moduli squared of the S- and P-wave recoil transversity amplitudes. The results show the presence of ‘‘A1’’ exchange in the unnatural nucleon-helicity-nonflip amplitudes. The natural ‘‘A2’’-exchange amplitudes dominate at large t. In the range 0.2≤-t≤0.4 (GeV/c)2 the mass dependence shows that the unnatural exchange amplitudes with transversity ‘‘down’’ are generally larger than those with transversity ‘‘up.’’ The opposite is true for the natural exchange. In this range of t and at the ρ0 mass, the P-wave unnatural amplitudes with both transversities contribute in equal amounts while the production by natural exchange proceeds entirely with transversity up. We observe rapid changes of the moduli within the ρ0 mass range and variations of the width and the position of the ρ0 peak in spin-averaged partial-wave cross sections. These structures have not been seen in previous polarization experiments and reveal spin dependence of ρ0 production. Our bounds cannot exclude an S-wave resonance in the range 700–800 MeV. The results emphasize the need for a better experimental and theoretical understanding of the mass dependence of the production mechanism.
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'Y' components of RHO.
'X' components of RHO.
The polarization in K + n↑ → K 0 p has been measured at 6 and 12 GeV/ c in the interval 0.1 < |t| < 1.0 using a polarized deuteron target. The results are compared to predictions from SU(3), exchange degeneracy (EXD) and line reserval, and from various phenomenological models.
NARROW BINS.
WIDE BINS.
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The ratio of the analysing powers for quasi-elastic pp scattering in carbon and for elastic scattering on free protons was measured fromT = 0.52 to 2.8 GeV by scattering of the SATURNE II polarized proton beam on carbon and CH2. It was found to have a maximum at about 0.8 GeV. The energy dependence for quasielastic scattering on carbon had not been measured before above 1 GeV. The observed effect was not expected from simple models.
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Measurements of energy weighted angular correlations in electron positron annihilations at c.m. energies of 22 GeV and 34 GeV are presented.
ENERGY-ENERGY CORRELATIONS FOR FINAL STATE PARTICLES.
ENERGY-ENERGY CORRELATIONS FOR PRIMORDIAL HADRONS.
ASSYMETRY IN ENERGY CORRELATIONS FOR FINAL STATE PARTICLES.
The differential cross sections for neutron-proton elastic charge-exchange scattering have been measured with a two-arm technique for incident neutron momenta between 22 and 65 GeV/ c and for values of the momentum transfer squared between 0.002 and 0.8 (GeV/ c ) 2 . The sharp forward peak observed previously at lower energies is also present at momenta up to 65 GeV/ c ; however the s dependence of the cross section is slowing down.
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We have measured the cross section, the distribution of scattering angles, and the distribution of noncoplanarity angles for electron-positron elastic scattering at 5 GeV c. m. energy. An analysis based on 230 events with scattering angles between 50 and 130° yields a ratio of the experimental to theoretical quantum-electrodynamic cross section of 1.03 ± 0.09. The scattering-angle and noncoplanarity-angle distributions are also found to be in excellent agreement with the quantum-electrodynamic predictions.
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MISPRINT CORRECTED DATA PRESENTED BY D.I.PATALAKHA.
The highest-energy measurement of ΔσL(pp) and the first ever measurement of ΔσL(p¯p), the differences between proton-proton and antiproton-proton total cross sections for pure longitudinal spin states, are described. Data were taken using 200-GeV/c polarized beams incident on a polarized-proton target. The results are measured to be ΔσL(pp)=−42±48(stat)±53(syst) μb and ΔσL(p¯p)=−256±124(stat)±109(syst) μb. Many tests of systematic effects were investigated and are described, and a comparison to theoretical predictions is also given. Measurements of parity nonconservation at 200 GeV/c in proton scattering and the first ever of antiproton scattering have also been derived from these data. The values are consistent with zero at the 10−5 level.
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Proton-proton elastic scattering has been measured at the CERN Intersecting Storage Rings in the four-momentum transfer range 0.001 ⩽… t …⩽ 0.015 GeV 2 at centre-of-mass energies of 23 and 31 GeV. The detection of Coulomb scattering and of its interference with nuclear scattering leads to the determination of the real part of the nuclear amplitude and of the total proton-proton cross section by the optical theorem.
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