The production of photons ine+e−→γ+hadrons is investigated at three centre of mass energies around 14, 22 and 34 GeV. On average, photons carry 25% of the total available energy, with a multiplicity similar to the charged multiplicity. The inclusive photon spectra are found to scale with the centre of mass energy as a function of the Feynman variablex. π0 and η mesons are reconstructed from their decay photons. The slopes of the spectra are similar to that for charged pions and approximate scaling is observed for π0 production. The mean π0 and η multiplicities are given. The observed photon yield can be fully accounted for by hadron decays and initial state radiation. However, up to one extra photon per event from other sources cannot be excluded.
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Multiplicity distributions of charged particles for inelastic, non single-diffractive events in proton-antiproton collisions at a centre of mass energy of 540 GeV are presented for various pseudorapidity (Δη) intervals. The widths of the multiplicity distributions, scaled to their means, increase as Δη is made smaller, and the deviation from a Poisson distribution becomes progressively more pronounced. It is found that the data are remarkably well described by a negative binomial distribution. The parameters of the distributions vary smoothly with the size of the acceptance interval.
Data for full phase space.
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Cross sections are presented for the inclusive photoproduction of KS0, Λ, Λ¯, Ξ−, Ξ¯−, Σ0, and Σ*±(1385) at 20 GeV. An upper limit to Ω− production is also given. The data come from 284 000 hadronic events photoproduced in the SLAC 1-m hydrogen-bubble-chamber hybrid facility exposed to a nearly monochromatic, polarized 20-GeV backscattered photon beam. A comparison of the KS0, Λ, Λ¯, and Ξ− rates per inelastic event to π±p data show that γp rates are consistent with being higher than the π±p rates, providing evidence of an ss¯ component of the photon. The pair cross sections for KS0KS0, KS0Λ, KSoΛ¯, and ΛΛ¯ are presented. The xF distributions of the Λ, Λ¯, and Ξ− are compared to a quark-diquark fusion model, giving information on strange-baryon photoproduction mechanisms.
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Toward the goal of experimentally determining the p-p elastic-scattering amplitudes at 6 GeV/c, we have measured a number of triple- and double-spin correlation parameters over the ‖t‖ range between 0.2 and 1.0 (GeV/c)2. These new data permit the first nucleon-nucleon amplitude determination in the multi-GeV energy range. Polarized beams from the Argonne Zero Gradient Synchrotron and polarized targets were utilized. The polarization of the recoil proton was measured with a carbon polarimeter. A total of 14 different spin observables were measured (five spin transfer, four depolarization, and five triple-spin correlation parameters). These have been combined with earlier results, resulting in a data set of typically 30 measurements of 20 different spin observables for each of six ‖t‖ values between 0.2 and 1.0 (GeV/c)2. A solution for the amplitudes has been found at each ‖t‖, and comparisons are presented with several different models. The spin-nonflip helicity amplitudes are found to be much larger than the spin-flip amplitudes.
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A search has been made for particles with charge Q = 1 3 , Q = 2 3 and Q = 4 3 produced in e + e − annihilation using the ARGUS detector at the e + e − storage ring DORIS, operating at a centre of mass energy around 10 GeV. No candidate events were found in 84.5 pb −1 of collected data. Upper limits are established for the cross section for the production of fractionally charged particles with masses up to 4 GeV c 2 , improving on previously obtained limits.
Two different models (I and II) are considered (see text).
Using the UA5 detector, the inclusive central production of Ks<sup loc="post">0</sup> and K<sup loc="post">±</sup> mesons has been measured in non-single-diffractive interactions at the CERN SPS <math altimg="si1.gif"><ovl type="bar" style="s">p</ovl>p</math> Collider at a c.m. energy of 540 GeV. The average transverse momentum is found to be 〈pT〉 = 0.57±0.03 GeV/c in the rapidity range |y|<2.5, which is an increase of about 30% over the top ISR energy. The K/π ratio has increased from about 8% at ISR energies to 9.5±0.9±0.7% (the last error is systematic) at 540 GeV. The average number of Ks<sup loc="post">0</sup> per non-single-diffractive event is 1.1±0.1 and the inclusive inelastic cross section is estimated at 49±5 mb.
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We present high statistics measurements of the energy-energy correlation (EEC) and its related asymmetry (AEEC) ine+e− annihilation at a c.m. energy of 34.6 GeV. We find that the energy dependence as well as the large angle behaviour of the latter are well described by perturbative QCD calculations toOα(s2). Non-perturbative effects are estimated with the help of fragmentation models in which different jet topologies are separated using (ɛ, δ) cuts, and found to be small. The extracted values of\(\Lambda _{\overline {MS} }\) lie between 100 and 300 MeV.
Corrected energy-energy correlation data.
CORRECTED FORWARD-BACKWARD ASYMMETRY.
The fragmentation functions of u-quarks into positive and negative pions are determined from an analysis of identified pions produced in deep inelastic muon-deuterium scattering. The method adopted is not sensitive to the knowledge of the primary quark distribution functions. The fragmentation of u quarks to positive pions is found to fall less steeply in z than that to negative pions as expected in the quark parton model.
Here Z=P(P=3)/E(P=3).
Antiproton-proton and proton-proton small-angle elastic scattering was measured for centre-of-mass energies s =30.6, 52.8 and 62.3 GeV at the CERN Intersectung Storage Rings. In addition, proton-proton elastic scattering was measured at s =23.5 GeV . Using the optical theorem, total cross sections are obtained with an accuracy of about 0.5% for proton-proton scattering and about 1% for antiproton-proton scattering. The measurement of the interference of the Coulomb scattering and the hadronic scattering permits a determination of the ratio of the real-to-imaginary part of the forward hadronic scattering amplitude. Also presented are measurements of the hadronic slope parameter.
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The antiproton-helium reaction cross section has been measured at 19.6 and 48.7 MeV with a streamer chamber in a magnetic field. Charged prongs and negative pion multiplicities and cross sections for the production of 3 He are given. A comparison with p 2 H is performed. he previously obtained 179.6 MeV results are also taken into account.
CROSS SECTIONS FOR THE INELASTIC EVENTS IN THE PBAR HE INTERACTIONS.
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