Proton-proton elastic scattering has been measured in the region 4.9<|t|<12.1 GeV2 at a beam momentum of 201 GeV/c. If the form exp(At) is fitted to the data, the exponent A gradually changes from 1.5 to 0.9 GeV−2 over our t range. The data are consistent with the form exp(−6.6p⊥). A comparison with intersecting storage ring results shows that in this kinematical region the slopes are about the same, but dσdt at fixed t is still dropping with energy.
7904 ELASTIC EVENTS.
1030 ELASTIC EVENTS.
We report measurements of the polarization parameters in π+p and π−p elastic scattering at an incident momentum of 100 GeV/c. The results cover the range 0.18<~−t<~1.4 GeV2 and are in agreement with current Regge-model predictions.
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THE AVERAGE PHASE IS -130.9 +- 2.7 DEG (NO EXPLICIT MOMENTUM DEPENDENCE). USING ABS(ETA+-) = 2.3*10**-3.
REGENERATION AMPLITUDE ASSUMING MOMENTUM INDEPENDENT CONSTANT PHASE.
CROSS SECTION DIFFERENCES ASSUMING MOMENTUM INDEPENDENT CONSTANT PHASE.
We report on a study of 15-GeV/c π+p interactions of all topologies using the SLAC 82-in. hydrogen bubble chamber. A description is given of the automatic pattern-recognition techniques used to measure the events. Cross sections are given for meson-resonance production in all topologies. Evidence is presented for a new resonance decaying to five pions. A measurement is made of the branching ratios of the g meson. A study is made of low-mass enhancements in the diffractively produced ρπ, fπ, and gπ channels, and a search is made for nondiffractive production of the A1 meson.
TOPOLOGICAL CROSS SECTIONS.
FITTED EVENTS CROSS SECTIONS.
RESONANCE PRODUCTION CROSS SECTIONS.
Inclusive production of Λ0 hyperons by 300-GeV protons has been measured at fixed production angles in the laboratory between 0 and 9 mrad and laboratory momenta from 65 to 300 GeV/c. Three different solid targets were used: beryllium, copper, and lead. The A dependence of the data is suggestive of a collision model in which the hadron loses energy and gains transverse momentum as it leaves the nucleus. The experimental results are compared to such a model, and the implications are discussed.
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New results on a high statistics measurement of pion-nucleon charge exchange scattering at 40 GeV/ c , extending in momentum transfer up to − t = 1.8 (GeV/ c ) 2 , are reported and compared with an optical impact parameter model, together with previous data for the reaction π − p → ηn at the same energy. The imaginary part of the pole trajectory b 0 ( s ) is determined from the slope of the tangent to the maxima of (−t) 1 2 d σ d t . The linear increase of Im b 0 ( s ) with log s , which has been observed at low energies, continues up to 40 GeV/ c .
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AT SMALL -T, THE BINNING TENDS TO SMEAR OUT THE FORWARD DIP.
We measured 30 000 wide-angle electron-positron pairs from the reaction γ+p→p+e++e− in the invariant-mass region 500≤m≤1060 MeV. The photoproduction amplitudes of the ρ, ω and ϕ mesons were measured to deviate from being pure imaginary by 37.5°−3.1°+2.8°, 29.6°−12.9°+15.5°, 3.4°−4.2°+5.3°,respectively.
DEVIATION OF VECTOR MESON PHOTOPRODUCTION PHASES FROM PURE IMAGINARY.
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The production of neutral kaons in the reaction K + p → K n + X is studied at the incident momentum of 32 GeV/ c . Inclusive cross sections and single-particle distributions are presented and compared with the data at lower energies. The total inclusive cross section amounts to 7.9 ± 0.3 mb at 32 GeV/ c and is significantly higher than at lower energies due to the rapid rise of multikaon production. The fraction of K n 's coming from the decay of the K ∗ resonances stays roughly constant with energy between 8.2 and 32 GeV/ c . In the central and beam fragmentation regions the single-particle distributions reveal no energy dependence between the 16 and 32 GeV/ c data in contrast with the behaviour at lower energies, while in the proton fragmentation region the data are compatible with the trend observed at lower energies and with theoretical expectations.
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A study of the inclusive and semi-inclusive Λ and Λ production in K + p interactions at 32 GeV/ c is presented. The inclusive cross sections for Λ and Λ amount to 0.78 ± 0.05 and 0.42 ± 0.04 mb thus showing a remarkable growth between 16 and 32 GeV/ c with a factor of 1.7 for Λ and 2.8 for Λ . Target and beam fragmentation processes are found to be dominant for Λ and Λ production respectively with the following lower limits for the corresponding cross sections: σ(p → K + ʌ) > 0.5 mb and σ(K + → p ʌ ) > 0.3 mb . Although the early scaling conditions are fulfilled for the Λ production in the target fragmentation region, and Λ production in the beam fragmentation region, scaling is not observed between 16 and 32 GeV/ c in the x and p T 2 Feynman variables. The Λ production is found to be very similar in the K + p inclusive reaction at 32 GeV/ c and in the semi-inclusive reaction K − p → Λ K K X at the same energy. The Λ Λ pair production cross section increases significantly in K + p interactions from 16 to 32 GeV/ c where it reaches the value σ Λ Λ = 47 ± 11 μ b . The cross sections for Λ or Λ produced in association with an identified proton are also given and discussed.
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