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-.
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.
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.
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R measurement.
D* cross sections.
We have searched for the lepton-flavor-violating decay D0→e±μ∓ in 204 pb−1 of e+e− annihilation data at Ec.m.=29 GeV from the Mark II detector. No candidates were found; we estimate an upper limit on the cross section times branching ratio of σ(e+e−→D0,D¯0; inclusive)B(D0→e±μ∓)<0.35 pb at the 90% confidence level. Simple assumptions yield the rough limit B(D0→e±μ∓)<2.1×10−3. AE.
No description provided.
Neutral D ∗ meson production in e + e − annihilation at √ s =29 GeV has been studied using the high resolution spectrometer. The decay of D ∗0 into D 0 γ, where the D 0 decays into K −π + , has been observed. The production cross section in units of the point cross section is 0.63±0.22 for fractional energy Z ⩾0.5. The fragmentation function is compared with that of the D ∗+ meson measured in the same experiment.
No description provided.
Assuming additionaly BR(D0-->K PI) of 0.56 +- 0.005.
Corresponding R value.
We present inclusive ϱ ±,0 and ω cross sections in the beam fragmentation region of π + p interactions at 250 GeV/ c . The near equality of the ϱ + and ϱ 0 cross sections implies suppression of valence quark recombination in forward vector meson production.
No description provided.
We compare the p T dependence of pion, kaon and proton production cross sections in the central rapidity region in e + e − annihilation events and in proton-proton collisions at ISR energies. We find similarities both in the p T dependence of cross sections and in the particle composition as a function of p T , in agreement with the hypothesis of a universal mechanism of particle production.
Numerical values requested from authors.
Data are presented on inclusive π0 production in the forward c.m. hemisphere (xF>0.025) in π+p,K+p andpp interactions at 250 GeV/c. These data are compared to results at other energies and interpreted in terms of quark-parton models.
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Systematic errors are at least 25 pct.
Forum