We report measurements of the inclusive π− and π+ yields in 24-GeV proton-proton collisions at θc.m.=90° for 2.2≤PT≤2.8 GeV/c. There is a high-PT deficit, rather than excess, at this incident energy.
THIS DATA IS FROM AN 'UNBIASED TRIGGER' WHICH RESPONDS TO ANY CHARGED PARTICLE.
THIS DATA IS FROM AN 'ELECTRON TRIGGER' WHICH RESPONDS ONLY TO PARTICLES THAT ARE ABOVE THRESHOLD IN > OR = 2 OF THE 3 CERENKOV COUNTERS IN THE LEAD- GLASS DETECTORS.
THIS DATA IS FROM AN 'ELECTRON TRIGGER' WHICH RESPONDS ONLY TO PARTICLES THAT ARE ABOVE THRESHOLD IN > OR = 2 OF THE 3 CERENKOV COUNTERS IN THE LEAD- GLASS DETECTORS.
Final states produced by charged baryon exchange in π − p interactions at 12 GeV/ c laboratory momentum have been studied. Forward neutrons with momenta determined by a calorimeter to be greater than 8.5 ± 1.4 GeV/ c triggered the SLAC 40-inch hydrogen bubble chamber which operated at a 10 Hz expansion rate. We report data on the reactions π − p→n π − π + , π − p→n π − π + π 0 , and π − p→n π − π − π + π + . In π − n π − p→n π + , production of ϱ and f mesons is observed. Differential cross sections are derived and compared with data at lower incident momentum and with theoretical models. In π − p→n π − π + π 0 , ω production is observed with a differential cross section having a deep near u ′= 0.2 (GeV/ c ) 2 . In π − p→n π − π − π + π + , Δ − , ϱ and f production is observed . The observed mass distributions appear to indicate the production of wide resonaces decaying into ϱππ. Some evidence for ϱ-ω interference is also observed.
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CORRECTED FOR BACKGROUND.
Measurements of inclusive scattering in the target-fragmentation region are extended to higher incident energy. The combined data set shows departures from an approach to the asymptotic scaling limit as A+Bs−12 that are significant even at the highest energies. When these departures are taken into account, the data approach a limit that is consistent with equal cross sections induced by particles and antiparticles and with Pomeron factorization. The corrections to A+Bs−12 are so large that detailed tests of Mueller-Regge relationships are not conclusive.
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We report the 24-GeV/c inclusive π− yield near θc.m.=90° for 0.5<~PT≲2.2 GeV/c. No high-PT excess is seen at this energy. In addition we have obtained the inclusive γ-ray yield from a measurement of low-mass e+e− pairs. This yield is compared with that expected from π0-, η-, and ω-meson decay, to provide limits on possible direct photon production.
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The missing-mass technique has been used to study the spectra of neutral mesons produced by 2- and 3-Gev protons in the reaction p+d→He3+x0. Cross sections (dσdΩc.m.) of about 10−34 cm2/sr were observed for the π, η, and ω for 3-GeV protons. A peak with a much smaller cross section was observed at a mass of 956 MeV. We have tentatively identified this peak as the η′. Cross sections for the π and η were nearly a factor of 10 larger at 2 GeV than at 3 GeV. Deviations from simple phase space were observed near the two-pion threshold in both 2-GeV and 3-GeV data. Details of the experimental method and of the results are presented.
Axis error includes +- 0.0/0.0 contribution (?////).
The asymmetry of π o and π + photoproduction from hydrogen has been measured. The π o -mesons were detected at 130° cms with E γ ranged from 0.9 to 1.65 GeV, and the π + -mesons at 40° cms with E γ ranged from 0.9 to 1.2 GeV. The results agree with model predictions of single pion photoproduction in the resonance region using fixed- t dispersion relations.
Axis error includes +- 0.0/0.0 contribution (?////).
Axis error includes +- 0.0/0.0 contribution (?////).
Axis error includes +- 0.0/0.0 contribution (?////).
We have extracted the strong interaction form factors from K o e3 and K o μ3 data of our previously reported K o L experiment in a manner which does not assume an explicit q 2 = ( p K − p π ) 2 dependence. We present the unparameterized form factors ƒ + (q 2 ) from the K o L → πeν and K o L → πμν modes and ƒ o (q 2 ) and ξ ( q 2 ) from the K o L → πμν data. A comparison of these unparameterized results is made with the results of the Dalitz plot analyses.
The conventional form factor f+ is studied.
We have measured the cross sections for these reactions and the cross sections of resonances produced in them. The production of Y ∗± (1385) , ϱ o (765), and f o (1260) is observed in the first reaction; ϱ o (765) in the second; Y ∗−,o (1385), ω o (748), B − (1235), probably ϱ o,− (765), and an enhancement we interpret to be the J P = 1 2 − Σ o (1750) in the third. Single particle longitudinal momentum distributions and average values of transverse momentum are presented. The observed single particle production angular distributions show good qualitative but not quantitative agreement with the Reggeized multiperipheral model of Chan, Loskiewicz, and Allison. We found strong disagreement between the amounts of observed resonance production and the results of the multiperipheral model of Plahte and Roberts that is based on the models of Chan et al. and Veneziano. However, we included isospin effects only in an approximate manner.
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Resonance production in the above reactions containing a proton in the final state is characterized primarily by the production of K ∗− (890). The events with a final state neutron are characterized by the production of either K ∗− (890) or Δ − (1236), but very little double resonance production. Cross sections are presented. Exponential slopes for the momentum-transfer distributions of the K ∗− (890) and Δ − (1236) were determined and found to be much smaller than for elastic scattering. For the π − π − p K 0 events the spin density matrix elements for the decay of the K ∗− (890) in the Jackson frame imply alignment. Single particle longitudinal momentum distributions and average values of transverse momentum are presented. The single particle production angular distributions of all three reactions were compared with the results of the Reggeized multiperipheral model of Chan, Loskiewicz, and Allison (CLA) modified to include resonance production. Good qualitative agreement was found. The data from the π − π − p K 0 events were also compared with a multiperipheral model of Plahte and Roberts that is based on the CLA and Veneziano models.
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