A systematic study has been made of the reactions pp→pp and pp→pN* in the angular range from θlab=10∘ to θc.m.=90∘ at 3, 4, 5, 6, and 7 GeVc. An orthogonal dispersion magnetic spectrometer detected protons from interactions in hydrogen with momentum transfer (−t) in excess of 0.5 (GeV)2. Well-defined peaks in the missing-mass spectra occurred at average N* masses of 1240±6, 1508±2, and 1683±3 MeV with average full widths of 102±4, 92±3, and 110±4 MeV, respectively. Below 2400 MeV no other significant enhancements were found. The N* production cross sections dσdt near θc.m.=90∘ are in qualitative agreement with the predictions of the statistical model. For each isobar the differential cross section at fixed energy varies as exp(−vv0), where v≡[−tu(t+u)]; v0 varies systematically with energy and tends toward the same value (≈0.4 GeV2) for each isobar at the upper limit of our energy range.
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The energy dependence of the K−-nucleon total cross sections has been measured over the K− momentum range 0.98-3.98 Bev/c. K−−n cross sections were obtained by deuterium-hydrogen subtraction, with a correction for screening effects. There is evidence for structure in the T=0 K−-nucleon state in the momentum range 0.98-2.0 Bev/c. This structure is absent in the T=1 state. In addition, a measurement was made at 1.95 Bev/c of the angular distribution of the K−−p elastic scattering at small angles. The forward-scattering amplitude obtained from the data gives a ratio of real part to imaginary part 0.5±0.2 at 00. The corresponding ratio for π− mesons at this momentum was found to be 0.4−0.4+0.2. Measurements of the K−−p "elastic" charge exchange gives a cross section which falls from about 10 mb at 1 Bev/c to at most a few mb at 4 Bev/c.
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The interaction of 1.0-, 1.25-, and 2.0-Bev antiprotons with protons has been studied with the aid of a 4π solid-angle scintillation-counter detector system. The measured total cross sections at the above energies are 100, 89, and 80 mb, respectively. At each energy, the charge-exchange cross section is approximately 5 mb. The total elastic cross sections are 33, 28, and 25 mb, respectively, at the three energies. The angular distribution of elastic scattering has been fitted with a simple optical-model calculation.
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We present stdies of events triggered on two high-pT jets, produced inpp collisions at the CERN Intersecting Storage Rings (ISR) at\(\sqrt s \)=63 GeV, using a large solid angle calorimeter. The cross-section for producing two jets is measured in the dijet mass range 17–50 GeV/c2. A high-statistics sample of dijet events, where each jet has transverse energy above 10 GeV, is used to study the structure of jets and the associated event. We find the longitudinal fragmentation function to be similar to that of jets emerging frome+e− collisions but considerably harder than that observed at the Super Proton Synchrotron (SPS)\(p\bar p\) Collider. A steepening of the fragmentation function is observed when increasing the jet energy. Studies of the charge distribution in jets show that these predominantly originate from fragmenting valence quarks. The transverse energy and particle flows are presented as functions of the azimuthal distance from the jet axis.
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FRAGMENTATION FUNCTION FOR ET(JET) > 10 GEV.
The inclusive process π++P→K¯ *0(890)+X is studied at 16 GeV/c using a 2-m streamer chamber containing a central liquid hydrogen target. From photographs triggered by detection of a forward K− meson, the signal K¯ K−*0π+ is extracted. The inclusive rate for K¯ * production into the forward hemisphere σ(xF>0.3) is 115±27 μb; the pT2 distribution is found to have a slope constant of 3.3±0.6 (GeV/c)2. The Feynman-x distribution for K¯ *0 is consistent with a Kuti-Weisskopf model in which the valence and sea quarks of the incident pion interact with only the sea quarks of the target proton.
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We have studied inclusive production of KS0, Λ, and Λ¯ particles in 20-GeV γp interactions and have found features similar to those observed in both hadronic and leptonic interactions. The production cross sections, charged-particle multiplicities, and average Λ polarization are reported. Inclusive distributions of x and pT are shown and discussed in terms of quark fragmentation models. Production cross sections for K*(890) and Σ*(1385) are also reported.
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Inclusive V0 production in 6.5-GeV/c K−p interactions is studied using the ANL 12-ft-diameter hydrogen bubble chamber. The total cross sections for inclusive K¯0 and Λ0 production are σ(K¯0)=7.98±0.49 mb and σ(Λ0)=3.94±0.24 mb. Semi-inclusive differential cross sections are determined as functions of Feynman x and transverse momentum squared of the V0's and of four-momentum transfer to the V0. The average charge multiplicity, the ratio 〈nc〉D, and the correlation function f2cc for the neutrally charged hadronic system recoiling from the V0 are determined as functions of the mass of the recoiling system. Results are used to examine universal aspects of multiparticle production.
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