Single and joint decay angular distributions in the reaction p p → Δ ++ Δ ++ at 9.13 GeV/ c are discussed in the framework of single and double statistical tensors. The t dependence of 12 double statistical tensors is presented. Cross sections for p p → p p π + π − and p p → Δ ++ Δ ++ are determined to be 2.60 ± 0.10 and 0.90 ± 0.10 mb respectively. The results obtained are compared with other experiments mainly at 5.7 and 12 GeV/ c .
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FROM FITTING DECAY ANGULAR DISTRIBUTIONS OF BOTH ISOBARS ADDED.
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FOUR PION RESONANCE CALLED RHO(1.71) BY AUTHORS. DECAY IS CONSISTENT WITH 100 PCT <RHO0 RHO-> MODE.
Cross sections are given for the various exclusive reactions K − p→ Λ 0 + n pions, as well as for quasi two-body final states involving ϱ 0 , ω 0 and Y 1 ∗ (1385) resonance production. The general features of Λ 0 production are presented as a function of the pion multiplicity n . Production of Y 1 ∗+ (1385) is clearly observed at all multiplicities while the Y 1 ∗− (1385) signals grow with the multiplicity, as expected in a non-exotic exchange picture. The polarisation of the Λ 0 is consistent with zero everywhere, except when it is a decay product of Y 1 ∗ (1385), when non-zero values are found for odd values of n . The reactions Λ 0 + 2π and Λ 0 + 3π are analysed in terms of the Plahte-Roberts model and good overall agreement is obtained for the various effective mass distributions and the p L ∗ , p T and cos θ distributions for the individual particles.
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The reactions K + n → K + π + π − n, K + n → K 0 π + π − p and K + n → K + π − π 0 p have b investigated in a 3.8 event/μb K + d bubble chamber experiment with incident momenta of 2.2, 2.45 and 2.7 GeV/ c . Channel cross sections are given and the general characteristics of the production processes described. The isobar model is used in an attempt to determine the spin-parity structure of the final states.
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We present data on the inclusive neutron spectra produced in the forward direction by the interactions of 23.85 GeV/ c protons in a copper target. The results are in good agreement with the predictions of the triple-Regge model.
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An accurate measurement of d σ d Ω (π − p → η n ) at 1531 MeV total energy (expanded) up to l = 4 Legendre polynomials) requires reconsideration of previous angular distribution fits which were expanded only up to l = 2 and of subsequent partial-wave analysis. An energy-dependent partial-wave analysis has been performed here for p η ∗ up to 450 MeV/ c . In addition to the well-known S 11 (1520 MeV) resonance, either the P 11 (1532 MeV) or the P 13 (1530 MeV) resonance is found to be strongly coupled to the η-n channel. In both cases, the P 11 (1729 MeV) resonance is needed as is the weakly coupled D 13 (1525 MeV) resonance. The decay states in the ηn channelare compared to the SU(3) and SU(6) W predictions.
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The modulus and the phase of the K L o −K S o regeneration amplitude on carbon have been measured. In a momentum range of 16–40 GeV/ c the phase is constant within experimental error bars and coincides with the regeneration phase on hydrogen. Both the modulus and the phase of the regeneration amplitude on carbon are in agreement with optical model predictions.
ASSUMING A CONSTANT PHASE INDEPENDENT OF MOMENTUM, THE CARBON REGENERATION AMPLITUDE HAS A PHASE OF -130 +- 17 DEG.
The neutron-proton elastic differential cross section has been measured for incident momenta between 10 and 70 GeV/c and for values of the momentum transfer squared between 0.1 and 2.8 (GeV/c) 2 . The forward peak and the break at about ∣ t ∣ = 1 (GeV/ c ) 2 are very similar to corresponding pp data.
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The asymmetry of the cross sections for the photoproduction of π + mesons on polarized protons γ + p↑ → π + + n has been studied in the four-momentum transfer range 0.1 ⩽ | t | ⩽ 1.25 (GeV/ c ) 2 for photon energies of 2.5, 3.4 and 5.0 GeV. The measurements were carried out on a polarized butanol target. Both particles in the final state were detected: the pion by a magnetic spectrometer, the recoil nucleon in a scintillation counter matrix. The asymmetry was found to be negative with values around −0.4.
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A study of the reaction π + p → p π + π o at 16 GeV/ c incident momentum has been made using the prism plot analysis to reject background events arising from elastic and multineutral contaminations and to separate different reaction channels ( ϱ + p, g + p, Δ + π + , Δ ++ π o , π + (p π o ) DD ). Cross sections, invariant mass distributions and production and decay angular distributions are presented. For the channel corresponding to proton diffraction dissociation strong violation of both s - and t -channel helicity conservation is found for low values of the (p π o ) mass. We demonstrate that the prism plot method provides a better separation of background events than conventional methods using kinematic cuts.
STATISTICAL ERRORS ONLY.
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