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No description provided.
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Axis error includes +- 2/2 contribution (Error in counter efficiency determination).
Electron momentum distribution.
Electron-positron pairs mass distribution.
The hadronic production of charmed states was studied in a two-arm spectrometer using a 205-GeV/c negative-pion beam incident upon a beryllium target. One arm, filled with dense absorber, triggered the detectors upon the passage of a muon with a moderate transverse momentum and a total momentum of at least 4 GeV/c. The other arm was an open-geometry magnetic spectrometer which had both neutral- and charged-particle identification capabilities. The apparatus, the data, and an invariant-mass-plot search for evidence of charmed-meson production through several charged-particle decay modes are described. The Kπ, Kππ, and Kπππ mass plots fail to reveal significant D-meson signals. Based upon the Kπ mass plots, the 95%-confidence upper limit on the DD¯ production cross section is found to be less than 51 μb per nucleon for the production models tested. A search for evidence of charged-D* production yields 30±16 combinations above background in association with the expected trigger muon charge. Interpreted as a D* signal, this excess corresponds to a model-dependent inclusive DD¯ production cross section of 34±18−9+14 μb per nucleon. Model-dependent upper limits on the ratio of the F to D cross sections are also presented.
Uncorrelated model for charmed mesons production.
'Correlated' model for pair of charmed mesons production.
Uncorrelated model for D/S+- mesons production.
Using a 320 GeV c π − beam incident on three different target materials Al, Fe, and U, the A -dependence of charm production is studied by measuring the yield of prompt single muons. Parametrizing the charm cross section as σ cc ( π − A) = σ 0 Aα the measured α values are α ( μ + ) = 0.76 ± 0.08 and α ( μ − ) = 0.83 ± 0.06.
No description provided.
Numbers of events per 10**6 incident PI-.
Single diffraction dissociation was measured in the reaction p¯p→p¯X at the centre-of-mass energy √ s = 546 GeV. The mass M of the system X was deduced from the pseudorapidity distribution of the observed charged tracks. The cross section of single diffraction dissociation for M 2 /s⩽0.05isσ sd =9.4 ± 0.7 mb. Comparison to the ISR data shows that σ sd increases with energy less fast than the total and the elastic cross sections.
No description provided.
We report evidence for beauty particle production through the observation of dimuon events from proton-antiproton collisions at energies of √ s =546 GeV and √ s =630 GeV at the CERN collider. Our data indicate that semi-leptonic decays of beauty particles are the dominant source of pairs of high- p T muons. The beauty flavour creation (gg or q¯q→b¯b ) cross-section needed to explain the dimuon rate is σ{ p¯p→b¯b +X, p b T 5 GeV/c, |η|<2.0}=(1.1±0.1±0.4) μb, which is in good agreement with QCD calculations. We also observe clear signals for ϒ→μ + μ − (hidden beauty) and high- p T J/ψ→μ + μ − , well above the backgraound of continuum muon pairs from the Drell-Yan mechanism.
No description provided.
The results of the cross-section determination of some two-prong final states with one neutral particle (1 C-fits) in ¯pp-interactions at 22.4 GeV/c are presented. These results have been obtained from pictures of the HBC “Ludmila”.
No description provided.
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NUCLEUS IS THE NUCLEUS OF EMULSION.
NUCLEUS IS THE NUCLEUS OF EMULSION.
NUCLEUS IS THE NUCLEUS OF EMULSION.
None
No description provided.
No description provided.
Nearly 40000 neutrino and antineutrino interactions in BEBC are compared to measure the differences between neon and deuterium in the quark and antiquark distributions and in the nucleon structure functions. The ratio of Ne to D cross sections indicates some decrease betweenx∼0.2 andx∼0.6. They distributions show there is no significant increase in the neon sea, but prefer a small decrease. Taken altogether, thex andy distributions and the measured total cross-sections indicate some change in the shape of the valence distributions. No significant dependence onA is observed for either the shape of the sea or the ratio of longitudinal to transverse cross-sections.
No description provided.
No description provided.
No description provided.
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