Cross sections for charge changing and particle production are measured for 32 S collisions with Al, Fe, Cu, Ag and Pb targets at 200 GeV/ c . The measured difference between the two cross sections is discussed. Results are compared with data obtained with an 16 O beam.
Charge changing cross section.
Production cross section.
Fermilab experiment 711 has investigated proton-nucleus collisions in which two high-transverse-momentum hadrons are produced forming high-mass ++, +-, and -- charged states, using an 800-GeV/c proton beam on targets of beryllium, aluminum, iron, and tungsten. Our data cover the range in dihadron mass from 6 to 15 GeV/c2. We show here that the dependence of the cross section on atomic weight A can be parametrized as Aα where α=1.043±0.011(stat)±0.025 (syst), and is independent of the charge state of the dihadron system.
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Using the ARGUS detector at thee+e− storage ring DORIS II, we have investigated inclusive production of π±,K±,Ks0 and\(\bar p\) in multihadron events at 9.98 GeV and in direct decays of the ϒ(1S) meson, i.e. from quark and gluon fragmentation. The most pronounced difference is the rate of baryon production. The Lund Monte Carlo program gives a reasonable qualitative description, although it cannot reproduce our data in detail.
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Single charged-particle inclusive cross sections for photon, pion and kaon beams on hydrogen at the CERN-SPS are presented as functions ofpT andxF. Data cover the range 0.0<pT<5.0 GeV/c and 0.0<xF<1.0 at incident momenta from 70 to 170 GeV/c. The comparison between photon- and hadron-induced data indicates a relative excess of particles withpT>1.6 GeV/c for the photon-induced data. Using the hadron-induced data to estimate the hadronic behaviour of the photon, the difference distributions and ratios of cross sections are a measure of the contribution of the point-like photon interactions. The data are compared with QCD calculations and show broadly similar features.
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This paper reports cross-section measurements for the ρ0 and K*(890) vector mesons produced in e+e− annihilation at s=29 GeV. The data, which were taken with the High Resolution Spectrometer operating at the SLAC colliding-beam facility PEP, correspond to an integrated luminosity of 291 pb−1. The measured multiplicities for fractional momentum x>0.05 are Nρ0=0.79±0.04 and NK*0(890)=0.53±0.04. The measured fragmentation functions agree well with the predictions of the Lund model and when extrapolated to threshold, the corresponding total multiplicities are Nρ0=0.90±0.05 and NK*0(890)=0.59±0.05.
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We present results on a high statistics study of the proton structure functions F 2 ( x , Q 2 ) and R = σ L / σ T measured in deep inelastic scattering of muons on a hydrogen target. The analysis is based on 1.8 × 10 6 events after all cuts, recorded at beam energies of 100, 120, 200 and 280 GeV and covering a kinematic range 0.06 ⩽ x ⩽ 0.80 and 7 GeV 2 ⩽ Q 2 ⩽260 GeV 2 . At small x , we find R to be different from zero in agreement with predictions of perturbative QCD.
THE AVERAGE VALUES OF Q**2 AT EACH OF THE X VALUES LISTED IN THIS TABLE ARE 15,20,20,25,30,35,40,45,50,50.
R=SIG(L)/SIG(T) IS TAKEN TO BE ZERO.
R=SIG(L)/SIG(T) IS TAKEN TO BE ZERO.
The analyzing power for elastic pd scattering at 3.5 GeV has been measured in the region 0.1⩽−t⩽1.5 (GeV/ c ) 2 , using the polarized proton beam at KEK. The angular distribution shows a behavior similar to that in the lower energy region. It is reproduced fairly well by the predictions of a multiple scattering model based on the Glauber theory.
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The reaction pp→p f (K + K − K + K − )p s in which the K + K − K + K − system is centrally produced has been studied at 300 GeV/ c . φφ production has been observed and the ratio σ (φK + K − )/ σ ( φφ ) is 1.0±0.3. The cross section for central production of φφ is found to be the same at 300 GeV/ c and 85 GeV/ c . An angular analysis of the φφ system favours J P =2 + over 0 − .
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Differential cross sections for the emission of intermediate-mass fragments (3≤Zf≤14) at 48.5° and 131.5° in the interaction of xenon with 1–19 GeV protons have been measured. The excitation functions rise sharply with energy up to ∼10 GeV and then level off. The energy spectra were fitted with an expression based on the phase transition droplet model. Excellent fits with reasonable parameters were obtained for Ep≥9 GeV. Below 6 GeV, the fits show an increasing contribution with decreasing energy from another mechanism, believed to be binary breakup. A droplet model fit to the cross sections ascribed to the multifragmentation component is able to reproduce the variation of the yields with both fragment mass and proton energy. The results are interpreted in terms of the phase diagram of nuclear matter.
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Scaled factorial moments, corrected for the shape of the single-particle pseudorapidity distribution, are analyzed in pseudorapidity and in two-dimensional (pseudorapidity and azimuth angle) space. An intermittent, power-law growth of the moments with decreasing bin size is found, with two-dimensional analysis revealing a much stronger effect than for one-dimensional for nucleus-nucleus data. The intermittent patterns are more evident for proton-nucleus than for nucleus-nucleus collisions, with the heaviest nucleus, S32, showing the weakest effect.
SEMICENTRAL EVENTS.
Forum