We have observed 217 (66) events of the process νp→νp (ν¯p→ν¯p) with an estimated background of 82 (28). The neutral-to-charged-current ratios are σ(νp→νp)σ(νn→μ−p)=0.11±0.02 and σ(ν¯p→ν¯p)σ(ν¯p→μ+n)=0.19±0.05 for 0.40
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Dimuon production is studied in 217-GeV/c π−-hydrogen and π−-beryllium collisions with a lead-glass array to detect photons associated with the ψ. The ψ−γ mass spectrum shows a 2.6-standard-deviation excess of events above background at ∼3.5 GeV. This excess, if attributed to the decay χ(∼3.5)→ψγ, implies that 0.70±0.28 of the ψ's are produced via radiative decay of one of the χ states.
E*D(SIG)/D(XL) is fitted by (1-X)**POWER.
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The cross section ratio of the elastic neutral current reaction ν p→ ν p to the quasi-elastic charged current reaction ν n→ μ − p has been measured in the kinematical region 0.3⩽ q 2 ⩽1.0 (GeV/ c ) 2 . The measured value is R M =0.17±0.08. Model dependent corrections are applied, especially for ν n→ ν n contamination, and the result is compared to various models.
(C=OBSERVED) and (C=CORRECTED) are the observed and corrected for the nuclear effects ratios.
Inclusive and semi-inclusive ρ 0 production are studied in 205 GeV/ c pp interactions. The number of ρ 0 per inelastic event is 0.33 ± 0.06, so that (13 ± 2)% of the π − are products of ϱ 0 decay. The ρ 0 are found to be produced mainly near y = 0 and tend to have larger average transverse momentum than do pions.
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Relative rates for deep inelastic neutrino and antineutrino scattering without a finalstate muon have been measured. For neutrinos the result is Rν=σ(νμ+nucleon→νμ+hadrons)σ(νμ+nucleon→μ−+hadrons)=0.11±0.05. The corresponding ratio for antineutrinos is Rν¯=0.32±0.09.
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In exposures of the Argonne National Laboratory 12-ft bubble chamber filled with hydrogen and deuterium to a neutrino beam, we have observed events consisting of (1) a single π+ meson originating in the liquid, and (2) a proton with an e+e− pair pointing to it. Only a small fraction of these events can be ascribed to known reactions such as np→nnπ+ and np→npπ0. The remaining events, which correspond to a signal of about 4.5 standard deviations, we ascribe to the reactions νp→νnπ+ and νpπ0.
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We report here additional positive results of a search for muonless neutrino- and anti-neutrino-induced events using an enriched antineutrino beam and a muon identifier of relatively high geometric detection efficiency. The ratio of muonless to muon event rates is observed to be R=0.20±0.05. We observe no background derived from ordinary neutrino or antineutrino interactions that is capable of explaining the muonless signal.
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