The charged-current cross sections for neutrinos and antineutrinos on nucleons in the energy range 20–200 GeV are given. Taken in conjunction with the previous Gargamelle results, they show that σ E is almost constant with energy for antineutrinos, and falls with energy for neutrinos. The value of 〈q 2 〉 E decreases with energy for both neutrinos and antineutrinos, and these deviations from exact Bjorken scaling are consistent with those observed in electron and muon inelastic scattering. We find no evidence for new heavy quark states with right-handed coupling.
Measured charged current total cross section.
Measured charged current total cross section.
We measured 30 000 wide-angle electron-positron pairs from the reaction γ+p→p+e++e− in the invariant-mass region 500≤m≤1060 MeV. The photoproduction amplitudes of the ρ, ω and ϕ mesons were measured to deviate from being pure imaginary by 37.5°−3.1°+2.8°, 29.6°−12.9°+15.5°, 3.4°−4.2°+5.3°,respectively.
DEVIATION OF VECTOR MESON PHOTOPRODUCTION PHASES FROM PURE IMAGINARY.
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Proton-proton elastic scattering has been measured in the region 4.9<|t|<12.1 GeV2 at a beam momentum of 201 GeV/c. If the form exp(At) is fitted to the data, the exponent A gradually changes from 1.5 to 0.9 GeV−2 over our t range. The data are consistent with the form exp(−6.6p⊥). A comparison with intersecting storage ring results shows that in this kinematical region the slopes are about the same, but dσdt at fixed t is still dropping with energy.
7904 ELASTIC EVENTS.
1030 ELASTIC EVENTS.
We measured dσdt for p+p→p+p at 11.75 GeV/c using the zero-gradient synchrotron 70% polarized-proton beam and a 65% polarized-proton target. We obtained the spin-orbit asymmetry parameter A and the spin-spin correlation parameter Cm out to P⊥2=4.2 (GeV/c)2. We found that A drops smoothly towards zero, but that Cnn increases abruptly near P⊥2=3.6 (GeV/c)2, where the exp(−1.4P⊥2) component of elastic scattering becomes dominant. This suggests that large-P⊥2 "hard" elastic scattering may occur mostly when the two proton spins are parallel.
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Measurements of the ν and ν¯ weak hadronic neutral-current total cross sections and hadron energy distributions are consistent with a V−A form for this current. They are three standard deviations from pure V, pure A, or a pure T form and unambiguously exclude V+A and any linear combination of S and P.
DATA FOR VARIOUS BEAM FOCUSING.
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Decay modes of the charmed mesons, D 0 and D + , are studied in e + e − annihilation data at 4.03 and 4.41 GeV c.m. energy. The products of cross section times branching ratio are measured for the K − π + , K − π + π + π − , K S π + π − and K − π + π + final states. Upper limits are established for the Cabibbo forbidden decays via π + π − , K + K − , K + K − π + , K + π + π − and π + π − π + . The K − π + π + π − final state is shown to be dominated by K − π + ρ 0 .
THESE PARTIAL CROSS SECTIONS ARE CONVERTED TO TOTAL D INCLUSIVE CROSS SECTIONS USING KNOWN BRANCHING RATIOS AND TABULATED IN M. PICCOLO ET AL., PL 86B, 220 (1979).
A study of the inclusive and semi-inclusive Λ and Λ production in K + p interactions at 32 GeV/ c is presented. The inclusive cross sections for Λ and Λ amount to 0.78 ± 0.05 and 0.42 ± 0.04 mb thus showing a remarkable growth between 16 and 32 GeV/ c with a factor of 1.7 for Λ and 2.8 for Λ . Target and beam fragmentation processes are found to be dominant for Λ and Λ production respectively with the following lower limits for the corresponding cross sections: σ(p → K + ʌ) > 0.5 mb and σ(K + → p ʌ ) > 0.3 mb . Although the early scaling conditions are fulfilled for the Λ production in the target fragmentation region, and Λ production in the beam fragmentation region, scaling is not observed between 16 and 32 GeV/ c in the x and p T 2 Feynman variables. The Λ production is found to be very similar in the K + p inclusive reaction at 32 GeV/ c and in the semi-inclusive reaction K − p → Λ K K X at the same energy. The Λ Λ pair production cross section increases significantly in K + p interactions from 16 to 32 GeV/ c where it reaches the value σ Λ Λ = 47 ± 11 μ b . The cross sections for Λ or Λ produced in association with an identified proton are also given and discussed.
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The production of neutral kaons in the reaction K + p → K n + X is studied at the incident momentum of 32 GeV/ c . Inclusive cross sections and single-particle distributions are presented and compared with the data at lower energies. The total inclusive cross section amounts to 7.9 ± 0.3 mb at 32 GeV/ c and is significantly higher than at lower energies due to the rapid rise of multikaon production. The fraction of K n 's coming from the decay of the K ∗ resonances stays roughly constant with energy between 8.2 and 32 GeV/ c . In the central and beam fragmentation regions the single-particle distributions reveal no energy dependence between the 16 and 32 GeV/ c data in contrast with the behaviour at lower energies, while in the proton fragmentation region the data are compatible with the trend observed at lower energies and with theoretical expectations.
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