We have analyzed the two-prong final states in π+p interactions at 3.9 GeVc. Our result for elastic scattering is σ (elastic) = 6.50±0.1 mb (statistical error only). We find the elastic slope to be 6.61±0.14 (GeVc)−2. We find the elastic forward cross section to be 40.0±1.4 mb(GeVc)2. We have applied a longitudinal-momentum analysis to the one-pion-production channel. We find the cross section for the reaction π++p→π++π0+p to be 2.30±0.06 mb and that for π++p→π++π++n to be 1.45±0.05 mb. For resonance-production cross sections in these channels we find Δ(1236)=0.60±0.07 mb, ρ(760)=0.86±0.06 mb, and diffraction dissociation = 1.69±0.11 mb. We find that we can satisfactorily fit all distributions in the one-pion-production channel without assuming any phase-space production. In the missing-mass channel we observe dominant Δ++(1236) production plus evidence for A2+ production.
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Results of a high-statistics study of elastic scattering and meson resonances produced by π−p interactions at 8 GeV/c are presented. Large statistics and small systematic errors permit examination of the complete kinematic region. Total differential cross sections are given for ρ0,−, f0, g0,−, Δ±, Δ0, and N* resonances. Spin-density matrix elements and Legendre-polynomial moments are given for ρ, f, and Δ resonances. The results for ρ0 and f0 resonances are compared with the predictions of a Regge-pole-exchange model. Properties of the above resonances are compared and discussed. In particular, we present evidence that the ρ0 and f0 production mechanisms are similar. The similarity of the g0 t distribution to that of the ρ0 and f0 suggests a common production mechanism for all three resonances.
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SLOPE REFERS TO EXPONENTIAL FIT IN U.
Results are presented onK+p elastic scattering and on the reactionK+p→K+pπ+π− at 70 GeV/c. For the
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INTEGRATION OVER RANGE OF ABS(T) FROM 0 TO 1 GEV.
We report results from a measurement of the inclusive diffraction dissociation of photons on hydrogen, γp→Xp, in the range 75<pγ<148 GeV/c, 0.02<‖t‖<0.1 (GeV/c)2, and MX2/s<0.1. Our data show an exponential t dependence and a dominant 1/MX2 behavior for MX2>4 GeV2. We test the finite-mass sum rule and, by comparing γp with π−p data obtained in the same apparatus, we test factorization.
EXTRACTED ELASTIC CROSS SECTIONS.
RESULTS OF EXPONENTIAL FITS TO ELASTIC CROSS SECTIONS.
DIFFERENTIAL CROSS SECTIONS FOR INELASTIC EVENTS.
On 8 K events of the reaction p p π + π − at 7.23 GeV/ c simple selection on angular parameters is performed yielding a sample of events with the typical features of diffraction dissociation. A cross section of 1.22 ± 0.08 mb (in two vertices) and a slope of the t distribution of 12.6 ± 1.0 GeV −2 for − t < 0.1 GeV 2 are obtained for the diffraction fraction dissociation p → p π + π − + c.c. Using an analogous selection procedure, another sample of events is isolated that is characterized by double resonance production. Cross sections for Δ Δ and Δ Δ ′ + c.c. production amount to 1.27 ± 0.09 mb and 0.23 ± 0.07 mb respectively. Diffraction dissociation and double resonance production together make up for 87% of the total cross section for the reaction p p → p p π + π − , which is 3.11 ± 0.13 mb.
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Results on exclusive double diffraction dissociation in (N π ) and (N ππ ) final states are reported for neutron-neutron interactions at √ s = 26.4 GeV and for the proton-neutron interactions at √ s = 37.2 GeV. The data have been obtained at the CERN intersecting storage rings using split field magnet detector with proton-deuteron and deuteron-deuteron colliding beams. Factorization is shown to be verified to a very high degree in both mass- and t -differential cross-sections. The data confirm the previously observed rise in the proton-proton double diffractive cross-section as a function of c.m. energy.
26.6 GEV/C INCIDENT BEAMS.
26.6 GEV/C INCIDENT BEAMS.
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Total cross section for inelastic diffraction.
We have measured the coherent nuclear production of low-mass K+ω systems in K+A collisions at 202.5 GeV. Results for carbon, copper, and lead targets are similar to those found for π+π+π− production in π+A reactions at the same energy.
M(K+ OMEGA) < 1.5 GEV.
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.
We present the results of a systematic analysis of charge-exchange double dissociation in proton-proton collisions at the CERN Intersecting Storage Rings. The data, obtained with the Split-Field Magnet detector, cover the entire ISR energy range between s = 23 GeV and s = 63 GeV at five standard energies.
CHARGE EXCHANGE DOUBLE DIFFRACTION DISSOCIATION OF PROTONS. THESE CROSS SECTIONS WERE REPORTED IN G. GOGGI ET AL., PL 72B, 265 (1977).
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