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Within the framework of the quark-parton model, the quark and anti-quark structure functions of the proton have been measured by fitting them to the distributions of the events in the Bjorkeny variable. The data used form the largest sample of neutrino and antineutrino interactions on a pure hydrogen target available, and come from exposures of BEBC to the CERN wide band neutrino and antineutrino beams. It is found that the ratiodv/uv of valence quark distributions falls with increasing Bjorkenx. In the context of the quark-parton model the results constrain the isospin composition of the accompanying diquark system. Models involving scattering from diquarks are in disagreement with the data.
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This Letter reports results of a search for radiative production, by e+e− annihilation of particles that interact only weakly in matter. The search has been made in the total data set of 115 pb−1 acquired with the ASP detector at the SLAC storage ring PEP (s=29 GeV). No anomalous signal was observed. The number of generations of light neutrinos has been limited to Nν<7.5 (90% confidence level). Limits are also placed on the masses of particles predicted to exist by models of supersymmetry.
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The weak coupling constants of the electron, gVe and gAe, are determined from measurements of the total and differential cross sections for the reaction νμe→νμe. The data also place limits of interest on the magnitudes of a neutrino charge radius and a possible neutrino magnetic dipole moment.
Neutrino beam 0 - 5 GeV.
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Cross sections for inclusive direct photon production in π−p, π+p, and pp collisions at 300 GeV/c are measured at transverse momenta pT up to 7 GeV/c (xT=0.6). For π−p→γX also the rapidity distribution is presented. The cross-section ratio σ(π−p→γX)/σ(π+p→γX) is found to be 1 at pT=4 GeV/c and rises with increasing pT. This observation signals the occurrence of valence-quark–antiquark annihilation. The results are in good agreement with QCD predictions.
THERE IS ALSO A 1 PCT UNCERTAINTY IN THE PT SCALE AND A 7 PCT UNCERTAINTY IN THE NORMALISATION.
Cross sections for inclusive π0 production at large transverse momentum pT were measured in π−p, π+p, and pp collisions at 300 GeV/c. The cross-section ratio σ(π−p→π0X)/σ(π+p→π0X) was found to be consistent with unity in the pT region of 1 to 5 GeV/c. The cross-section ratio σ(π+p→π0X)/σ(pp→π0X) however is growing with increasing pT and increasing π0 c.m.-system rapidity in agreement with parton-model expectations, where the partons in the pions have on average higher momenta than in the proton.
THERE IS ALSO A 1 PCT UNCERTAINTY IN THE PT SCALE AND A 7 PCT UNCERTAINTY IN THE NORMALISATION.
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.
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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”.
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