Antineutrino interactions in BEBC are compared to look for differences between the differential cross sections per nucleon in neon and in deuterium. The identical geometries, beam spectra and muon identification criteria and acceptances allow comparison with very small systematic errors. The results are compared in detail with μ and e scattering data from EMC and SLAC. We find no rise in the ratio d σ/ d x ( ν Ne )/σ/ d x ( ν D 2 ) at low x , independent of Q 2 up to Q 2 ∼ 14 GeV 2 .
VALUES OF Q**2 IN THIS TABLE ARE :- 1.07,2.59,4.33,6.14,7.67,8.28,6.35 (FOR ALL Q**2) AND :-,7.9,9.5,11.5,13.2,13.9,11.6 (FOR Q**2 > 4.5 ).
We present results for the differential cross sections of neutrinos and antineutrinos on nucleons in the energy range E = 2−200 GeV, from the BEBC and Gargamelle experiments. The structure functions F 2 , 2 χF 1 and χF 3 have been evaluated as a function of χ and q 2 . Deviations are observed from Bjorken scaling, which are very similar to those found in electron and muon inelastic scattering. For the Callan-Gross ratio, we find 2χF 1 F 2 = 0.80 ± 0.12 and the corresponding value for 〈R〉 = 〈 σ S σ T 〉 = 0.15 ± 0.10 . Our results are consistent with the Gross-Llewellyn-Smith sum rule; we measure ⩾2.5 ± 0.5 valence quarks per nucleon. Quark and antiquark distributions are given. The Nachtmann moments of F 2 and χF 3 are quantitatively consistent with the predictions from QCD. The value of the strong interaction parameter is λ = 0.74 ± 0.05 GeV without corrections, and 0.66 ± 0.05 GeV including α S 2 corrections. The moments of the gluon distribution are found to be positive and indicate an χ distribution of gluons which is comparable with that of the valence quarks.
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ERRORS SHOWN ARE STATISTCAL. STRUCTURE FUNCTIONS COMPUTED ASSUMING CALLAN-GROSS RELATION.
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The average transverse momentum squared, 〈 p ⊥ 2 〉, of hadrons is studied as a function of W 2 and of Q 2 for ν and ν interactions on an isoscalar target. An increase of 〈 p ⊥ 2 〉 with W 2 is observed for the hadrons emitted forward in the hadronic c.m.s. The p ⊥ dependence of the fragmentation function is found to factorise from the structure function at fixed W , but does not factorise at fixed Q 2 . Unlike the case of forward-going particles, the 〈 p ⊥ 2 〉 of hadrons going backward in the c.m.s. shows no strong dependence on W 2 .
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Exposures of the Ne/H 2 filled Big European Bubble Chamber (BEBC) to a dichromatic neutrino (antineutrino) beam produced by 400 GeV protons of the CERN SPS yielded ∼ 3100 events with a negative, and ∼ 1100 with a positive, muon. The neutrino flux is determined from the muon flux in the shielding. Assuming a linear energy dependence of the cross section, the values σ E between 20 and 200 GeV are found to be 0.657 ± 0.012 (stat.) ± 0.027 (syst.) and 0.309 ± 0.009 (stat.) ± 0.013 (syst.) cm 2 (GeV nucleon) −1 , for neutrinos and antineutrinos, respectively. The scaling variable q 2 E decreases significantly with increasing energy both for neutrinos and antineutrinos.
Measured charged current total cross section.
Measured charged current total cross section.
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The ratios of neutral current to charged current cross sections of neutrino and antineutrino interactions in heavy Ne/H 2 mixture have been measured in BEBC. The beam was the CERN SPS 200 GeV/ c narrow band beam. The ratios were obtained using a cut in the transverse momentum of the hadronic system. In the standard Glashow-Salam-Weinberg model, our results correspond to the value of sin 2 θ w = 0.182 ± 0.020 ± 0.012. By combining this experiment with data from a hydrogen target the coupling constants u L 2 and L 2 are found to be 0.15 ± 0.04 and 0.19 ± 0.05, respectively.
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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.