Search

The observed scaling violations of the nucleon structure functionF 2 and $$\bar q$$ have been analysed in the framework of perturbative QCD to determine the shape and magnitude of the gluon distribution. The data are in good agreement with leading order QCD, and the simultaneous use ofF 2 and $$\bar q$$ structure functions permits, for the first time, a reliable determination of the gluon structure function.

A large sample of opposite-sign dimuons, produced by the interaction of neutrinos and antineutrinos in iron, is analysed. The data agree very well with the hypothesis that the extra muon is the product of charm decay. They yield information on the strength and space-time structure of the charmproducing weak current. The strange-sea structure functionxs(x) is determined. The difference between neutrino and antineutrino dimuon production is analysed to provide a value of the Kobayashi-Maskawa weak mixing angleθ2.

Experimental evidence for the diffractive production ofΨmesons in weak neutral current reactions is reported. The spectrum-averaged cross section for this process isσdiff = (4.2±1.5) × 10−41cm2/nucleon, in agreement with gluonfusion models, but at variance with vector dominance calculations.

The scaling violations of the structure functionsF 2,xF 3, and $$\bar q$$ , as measured in deep-inelastic neutrino-nucleon scattering at high hadron massW, have been compared with the predictions of QCD and other candidate field theories of strong interactions. Non-asymptotically free theories with scalar and vector gluons are incompatible with the data. This leaves QCD as the only field theory that gives a consistent description of all the observed scaling violations. The data do not, however, permit a sensitive test of the existence of the gluon self-coupling.

The energy resolution and response of a segmented iron-scintillator total absorption calorimeter has been measured for pion energies from 10 to 140 GeV and for electron energies up to 50 GeV. A procedure has been found to weight individual counter responses for hadron showers which results in improved energy resolution at high energies and a nearly linear dependence of response on hadron energy above 30 GeV. There is evidence in the data that this weighting procedure compensates for fluctuations in energy deposition due to the electromagnetic component of the hadronic shower. For an iron sampling thickness of 2.5 cm the hadron energy resolution follows a 0.58 E law, while the resolution for electromagnetic showers is 0.23 E .

Inclusive charged-current interactions of high-energy neutrinos and antineutrinos have been studied with high statistics in a counter experiment at the CERN Super Proton Synchrotron. The energy dependence of the total cross-sections, the longitudinal structure function, and the nucleon structure functionsF2,xF3, and\(\bar q^{\bar v} \) are determined from these data. The analysis of theQ2-dependence of the structure functions is used to test quantum chromodynamics, to determine the scale parameter Λ and the gluon distribution in the nucleon.

The cross section ratios of neutral and charged current interactions induced by neutrinos and antineutrinos in iron have been measured in the 200 GeV narrow-band beam at the CERN SPS. We findRv=0.301±0.007 andRv=0.363±0.015 for a hadron energy cut of 10 GeV. The results are in agreement with the standard model of electroweak interactions. In the\(\overline {MS} \) renormalization scheme at the scale of theW boson mass\(\sin ^2 \hat \theta _W \left( {m_W } \right) = 0.226 \pm 0.012\) is obtained, where the error represents the experimental uncertainty. The theoretical uncertainty is estimated to beΔsin2θW=±0.006.

A new measurement of the ratio R = σ L / σ T of longitudinal and transverse structure functions in neutrino interactions on iron between 30 and 190 GeV neutrino energy is reported. The result is given as a function of the scale parameter x and the inelasticity ν of the interaction. The average value is R = 0.10 ± 0.07 around ν ≈ 50 GeV and is in accordance with a prediction from the QCD theory.

In the interactions of 400 GeV/c protons with copper nuclei, a flux of prompt neutrinos is observed. The reactions produced by these neutrinos in our apparatus appear consistent with those of electron- and muon-neutrinos. The prompt neutrino fluxes are interpreted as being due to associated production and subsequent semileptonic decay of charmed hadrons. The prompt flux ratio $$\bar v_\mu /v_\mu = 0.46_{ - 0.16}^{ + 0.21} $$ suggests a sizeable production of charmed baryons near the forward direction. The ratio of prompte −+e + toµ −+µ + event rates is 0.64 −0.15 +0.22 , where unity is expected frome-μ universality.

Among 305 children with leukemia, between one and fourteen years old, authors found 8 and in a comparative group ("individual matched pairs") 40 children with removed tonsils. The difference (2.62% tonsillectomized children in the leukemia-group, 13.11% in the comparative group) is highly significant. The frequency of tonsillectomy in childhood in Germany corresponds to the percentage of 13.11%. It has to be discussed, if there exists a causality between the state of the tonsils and the frequency of leukemia in childhood. The authors suggest further investigations of this highly interesting subject.