In a selected sample of 6770 charged current (CC) events of νp interactions with 〈 E ν 〉 = 43 GeV and 〈W〉 = 4.6 GeV , 359 K 0 , 180 Λ and 13 Λ have been observed, which corresponds to a corrected production rate at least one neutral strange particle in (17.4±0.8)% of the CC events. The ratio of the inclusive Λ to K 0 production cross section is found to be 0.26±0.03. The number of CC events containing at least one K 0 increases with increasing E ν and Q 2 , while the CC events containing at least one Λ remain practically constant. The fractions of the total hadronic energy carried by K 0 and Λ are found to be approximately the same in νp as in ep and μp interactions. In the hadronic c.m.s., the K 0 are produced mostly forwards, the Λ mostly backwards, with asymmetry parameters of +0.32±0.02 and −0.45±0.06, respectively. The total strange particle production cross section is estimated to be (25±4)% of the cross section for production of CC events with W >1.5 GeV and that for charm production (10±2)% of the CC cross section well above charm threshold ( W >3 GeV). The production of the resonances K ∗+ (890) and Σ + (1385) has been observed. The production rate of K ∗+ (890) is comparable to that of D ∗+ (2009), above the corresponding thresholds.
No description provided.
In an experiment with the 30-inch Hybrid Spectrometer at Fermilab we have obtained the inclusive and semi-inclusive production cross sections of the ϱ0 meson using a conventional background subtraction technique. Production cross sections for the ϱ0 are derived as a function of the Feynman scaling variablex, and the transverse variablespt2 andEt=(pt2+M2)1/2. The longitudinal distributions are compared with the (1−x) dependence of the proton and meson valence quark structure functions, using various forms of recombination and fragmentation models. The transverse distributions are compared with thermodynamic models. We give density matrix elements for the ϱ0 production from pions in the extreme forward region.
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Inclusive Ξ − production is studied in K − p interactions at 8.25 GeV/ c using about 8000 events. An analysis based on the triple-Regge model shows that the Λ α − Λ γ and Σ β − Σ δ exchanges explain the forward Ξ − production. Ξ(1530) properties are also studied and are found to be similar to those of Ξ − 's. Finally, a study of the production of Ω − based on 67 events shows that Ω's are also produced by hyperon exchange.
No description provided.
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We report a measurement of the cross section for the process γγ → π + π − at invariant masses 500 MeV/ c 2 < m ππ <2000 MeV/ c 2 . A value for the radiative width of the f(1270) tensor meson Γ f→ γγ = 3.6 ± 0.3 ± 0.5 KeV (helicity λ = 2) has been obtained from a fit to the observed ππ mass spectrum.
DATA REQUESTED FROM AUTHORS.
Total neutrino and antineutrino cross sections in the energy range 15 to 150 GeV, and the nucleon structure functions, F 2 ( x , Q 2 ) and xF 3 ( x , Q 2 ) in the Q 2 range 0.5 to 50 (GeV/ c ) 2 have been measured using a data sample of 3000 neutrino and 3800 antineutrino events. The structure functions show a weak Q 2 dependence at different x values.
Measured charged current total cross section.
Measured charged current total cross section.
ERRORS CONTAIN 10 P.C. SYSTEMATIC ERROR WHICH HAS BEEN LINEARLY ADDED TO THE STATISTICAL ERROR.
Inclusive π 0 production has been measured at the CERN Intersecting Storage Rings in αα and α p collisions near 90°, for p T between 2 and 5 GeV/c. The differential cross sections show a slower exponential fall-off with p T than has been observed in pp collisions at the corresponding nucleon-nucleon centre-of-mass energies at large p T . The ratio of the π 0 production cross sections for αα collisions to those for pp collisions is observed to be larger than 16.
No description provided.
No description provided.
The inclusive charged-hadron momentum spectra from the ψ and ψ′ decays produced in e+e− collisions at SPEAR are presented. The data were obtained with a small solid-angle, single-arm magnetic spectrometer with good particle-identification abilities centered at 90 degrees with respect to the beams. The particle-separated invariant cross sections are compared with data from e+e− collisions at s=4.8 and 7.3 GeV, obtained with the same spectrometer, in order to observe the difference between hadron production at the resonances and in the continuum.
AT J/PSI.
AT J/PSI.
AT J/PSI.
We present results on the experimental study of inelastic charged-current antineutrino-nucleon scattering in the energy range of 10–200 GeV. The data sample, consisting of about 6500 antineutrino-induced events, was obtained in the Fermilab 15 ft bubble chamber filled with a heavy neon-hydrogen mixture. The differential cross sections for ν μ N interactions are presented in terms of scaling variables x and y . The structure functions F 2 ν and xF 3 ν have been evaluated as functions of x and E ν . A deviation from the scaling hypothesis, similar to those found in other experiments on inelastic lepton-nucleon scattering, has been observed. The data are interpreted in the framework of the quark-parton model. Quark and antiquark distributions and their energy dependences are presented.
No description provided.
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The first observation of μ + e + events produced in antineutrino interactions using the Fermilab 15 ft bubble chamber is reported. The relative yield of μ + e + events is (4.8 −3.2 +5.3 ) × 10 −4 of all charged-current events with antineutrino energy greater than 10 GeV. The observed V 0 rate is 1.0 −1.0 +1.2 per μ + e + event. Possible sources of these events are discussed.
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Data from an exposure of BEBC filled with hydrogen to a wideband neutrino beam are analysed to yield the structure function F v p 2 ( x ) for x > 0.2. Using our results in combination with data from electron-proton and muon-proton scattering, the quark density ratio d/u is determined as a function of x . The dominance u at large x is clearly seen. The results are compared with theoretical predictions.
No description provided.
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