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This analysis is based on data from neutrino and antineutrino scattering on hydrogen and deuterium, obtained with BEBC in the (anti) neutrino wideband beam of the CERN SPS. The parton momentum distributions in the proton and the proton structure functions are determined in the range 0.01

Based on a QCD analysis of the parton momentum distributions in the proton, the ratior v =d v /u v of thed andu valence quark distributions is determined as function ofx in the range 0.01

Evidence is presented for diffractive production of ρ-mesons and of ρπ-systems invp and $$\bar \nu p$$ chargedcurrent interactions. In the (anti-)neutrino energy range 10 GeV

The production of the neutral strange particlesK 0, Λ and $$\bar \Lambda $$ invp and $$\bar vp$$ charged current interactions is studied in an experiment with the Big European Bubble Chamber. Mean multiplicities are measured as a function of the event variablesE v,W 2 andQ 2 and of the hadron variablesx F,z andp T 2 .K *± (892) and∑ *± (1385) signals are observed, whereas there is no evidence for∑ *- (1385) production invp scattering. Forward, backward and total mean multiplicities are found to compare well with the predictions of an empirical model for deep-inelastic reactions in the case of the strange mesonsK 0 andK *± (892) but less so for the strange baryons Λ, $$\bar \Lambda $$ and∑ *± (1385). The strange baryon multiplicities are used to obtain the decuplet to octet baryon production ratio and to assess the probabilities of auu orud system to break up.

Using data onvp and $$\bar vp$$ charged current interactions from a bubble chamber experiment with BEBC at CERN, the multiplicity distributions of charged hadrons are investigated. The analysis is based on ∼20000 events with incidentv and ∼10000 events with incident $$\bar v$$ . The invariant massW of the total hadronic system ranges from 3 GeV to ∼14 GeV. The experimental multiplicity distributions are fitted by the binomial function (for different intervals ofW and in different intervals of the rapidityy), by the Levy function and the lognormal function. All three parametrizations give acceptable values forX 2. For fixedW, forward and backward multiplicities are found to be uncorrelated. The normalized moments of the charged multiplicity distributions are measured as a function ofW. They show a violation of KNO scaling.

The coherent production of 3π systems by charged current antineutrino interactions on neon nuclei is studied in the bubble chamber BEBC exposed to the CERN SPS wide band beam. The coherent signal is attributed mainly to (ρπ) production, where the (ρπ) system is either non-resonant or comes from the decay of a1 mesons. The kinematical variables and the total cross section are compared with the predictions of the meson dominance model. © 1991 Springer-Verlag.

Using data obtained with the bubble chamber BEBC at CERN, the inclusivef2 (1270) meson production invp and\(\bar vp\) charged current reactions is studied. It is found thatf2 production occurs mainly in events with a hadronic invariant massW≳7 GeV. In these events, the averagef2 multiplicity is about half the average ρO multiplicity, and thexF andpT2 distributions of thef2 agree in shape with those of the ρO. The predictions of a semi-empirical model (Wells model) are in accord with the measured multiplicities atW>7 GeV, whereas at lowerW the model predicts too largef2 multiplicities.

Using data onvp and\(\bar vp\) charged current interactions from a bubble chamber experiment with BEBC at CERN, the average multiplicities of charged hadrons and pions are determined as functions ofW2 andQ2. The analysis is based on ∼20000 events with incidentv and ∼10000 events with incident\(\bar v\). In addition to the known dependence of the average multiplicity onW2 a weak dependence onQ2 for fixed intervals ofW is observed. ForW>2 GeV andQ2>0.1 GeV2 the average multiplicity of charged hadrons is well described by〈n〉=a1+a2ln(W2/GeV2)+a3ln(Q2/GeV2) witha1=0.465±0.053,a2=1.211±0.021,a3=0.103±0.014 for thevp anda1=−0.372±0.073,a2=1.245±0.028,a3=0.093±0.015 for the\(\bar vp\) reaction.

The diffractive production of charmed strangeD s * and possiblyD s mesons by neutrinos and antineutrinos on nucleons in hydrogen, deuterium and neon targets is observed. The slope parameter of thet distribution is 3.3±0.8 (GeV)−2. The production rate per charged current neutrino interaction with an isoscalar target times the D s + →φτ+ branching fraction is (1.03±0.27)×10−4.

Data from a neutrino and antineutrino hydrogen experiment with BEBC are used to investigate transverse properties of the produced charged hadrons. Measurements are presented on average transverse momenta of charged pions as functions of Feynman-x and the hadronic mass, on the transverse momentum flow within an event and on jet-related quantities. The main features of the data are well described by the LUND model. The data favour a version of the model in which soft gluon effects are included and the primordial transverse momentum of the quarks in the proton is small. Effects from 1st order QCD (hard gluon emission) are negligible.

Neutral kaon to negative pion production ratios fromvp and\(\bar vp\) charged current interactions in BEBC are presented and compared with LUND fragmentation model predictions. Good agreement is obtained with a strangeness suppression factor λ=0.203±0.014(stat)±0.010(sys). No evidence is seen for an energy dependence of λ in our kinematic region.

Data obtained with the bubble chamber BEBC at CERN are used for the first significant test of Adler's prediction for the neutrino and antineutrino-proton scattering cross sections at vanishing four-momentum transfer squaredQ2. An Extended Vector Meson Dominance Model (EVDM) is applied to extrapolate Adler's prediction to experimentally accessible values ofQ2. The data show good agreement with Adler's prediction forQ2→0 thus confirming the PCAC hypothesis in the kinematical region of high leptonic energy transfer ν>2 GeV. The good agreement of the data with the theoretical predictions also at higherQ2, where the EVDM terms are dominant, also supports this model. However, an EVDM calculation without PCAC is clearly ruled out by the data.

The production of the meson resonances ϱ(770) (all three charge states), η(550), ω(783) andf 2(1270) in $$\bar v$$ Ne and ν Ne charged current interactions is investigated in a bubble chamber experiment with BEBC at CERN. Except for thef 2, the main features of resonance production are reasonably well described by the Lund model, although the average resonance multiplicities are overestimated by the model by (67±30)%. The average multiplicities of all resonances, including thef 2, are well reproduced by a semiempirical model, whose parameters were determined from hadron interaction data.

Backward proton and pion production is studied in ν and {Mathematical expression} charged current interactions in neon. The results are compared with other experiments and theory. The complete backward proton data is compatible with protons produced by reinteractions in the nucleus. However in events with only one proton, muon variables appear correlated to those for the backward proton, as expected by the two-nucleon correlation model. © 1989 Springer-Verlag.

Data on the reactionsv μ p→ μ− pπ+ and $$ \bar v_\mu p \to \mu ^ + p\pi ^ - $$ in the Δ(1232) region are presented and a test of the PCAC hypothesis, using a modified version of the Adler model, is performed. The analysis is based on 1081 events in the neutrino and on 180 events in the antineutrino reaction, obtained in a bubble chamber experiment with BEBC at CERN. The experimental cross-sections for an invariant hadronic massW10 GeV are determined to be (0.628±0.059)·10−38 cm2 for the neutrino and (0.168±0.023)·10−38 cm2 for the antineutrino reaction. TheQ 2 andW distributions, the density matrix elements of the Δ resonance, and moments of the pion angular distribution are discussed. The data are found to be in good agreement with the Adler model in theQ 2 region below 1 GeV2. A maximum likelihood fit for the axial massm A in the axial-vector form factor yields a value ofm A =1.31±0.12 GeV. At lowQ 2 the data confirm the PCAC hypothesis and the discrepancy, formerly observed between the experimental and theoretical cross-sections forv μ p→ μ− pπ+ at low momentum transfers (Q 2≲0.2 GeV2), is understood as being due to inadequate pion ‘off-mass-shell’ corrections.

Within the framework of the quark-parton model, the quark and anti-quark structure functions of the proton have been measured by fitting them to the distributions of the events in the Bjorkeny variable. The data used form the largest sample of neutrino and antineutrino interactions on a pure hydrogen target available, and come from exposures of BEBC to the CERN wide band neutrino and antineutrino beams. It is found that the ratiodv/uv of valence quark distributions falls with increasing Bjorkenx. In the context of the quark-parton model the results constrain the isospin composition of the accompanying diquark system. Models involving scattering from diquarks are in disagreement with the data.

Lambda hyperons fromv p and\(\bar v\)p charged current interactions have been analysed for polarization. A significant polarization is observed for Λ particles in the quasi-elastic region for both types of interactions. Part of this polarization is due to the decay of highly polarized Σ(1385) resonances. The results are compared with simple predictions of the quark parton model.

A study is presented of μe events from an exposure of BEBC, filed with an heavyH 2/Ne mixture, to a wide band antineutrino beam at the CERN SPS. The promptμ + e − rate, based on the observation of 45 events withp μ>4 GeV/c andp e>0.8 GeV/c, is found to be 0.31±0.05±0.02%, in agreement with previous determinations made on much smaller statistics. The differential kinematical variables characterizing the events and the content of strange particles are as expected for the production of charmed hadrons which subsequently decay semi-leptonically. An upper limit of 2.0±10−4 at 90% C.L. is given for the production rate of promptμ + e + events. No evidence is found for a significant production of Beauty hadrons.

Usind data from avp and\(\bar v\)p experiment with BEBC at CERN, the rates for inclusive production ofD*+,Λc+ andD0 invp scattering and ofD*− in\(\bar v\)p scattering are measured. Some examples of the exclusive production ofD*+,Λc+ and∑c++ are given. The cross section for the reactionvp→μ−c++ is estimated.

The isoscalar nucleon structure functions F2(x, Q2) and xF3(x, Q2) are measured in the range 0

Nearly 40000 neutrino and antineutrino interactions in BEBC are compared to measure the differences between neon and deuterium in the quark and antiquark distributions and in the nucleon structure functions. The ratio of Ne to D cross sections indicates some decrease between x∼0.2 and x∼0.6. The y distributions show there is no significant increase in the neon sea, but prefer a small decrease. Taken altogether, the x and y distributions and the measured total cross-sections indicate some change in the shape of the valence distributions. No significant dependence on A is observed for either the shape of the sea or the ratio of longitudinal to transverse cross-sections. © 1987 Springer-Verlag., 0, 52 auteurs, SCOPUS: ar.j, info:eu-repo/semantics/published

A sample of over 25,000 fully measured neutrino and antineutrino charged current interactions in BEBC includes 192 dilepton candidates. The prompt signal after subtraction of background is 41 ±7μ+e-, 35±7μ+μ- events from {Mathematical expression} interactions, and 32±7μ-μ+ events from ν interactions. There are 2 trileptons, μ-μ-e+ and μ-μ-μ+. Results are compared with other experimental data and with the standard model. Limits to prompt like sign μ+e+, μ+μ+ and μ-μ- signals are given and compared with other experiments and with theoretical calculations. © 1985 Springer-Verlag., 47 auteurs, SCOPUS: ar.j, info:eu-repo/semantics/published

The cross section for coherent production of a single π- meson in charged current antineutrino interactions on neon nuclei has been measured in BEBC to be (175±25) 10-40 cm2/neon nucleus, averaged over the energy spectrum of the antineutrino wide band beam at the CERN SPS; this corresponds to (0.9±0.1) % of the total charged current {Mathematical expression} cross section. The distributions of kinematical variables are in agreement with theoretical predictions based on the PCAC hypothesis and the meson dominance model; in particular, the Q2 dependence is well described by a propagator containing a mass m=(1.35±0.18) GeV. The absolute value of the cross section is also in agreement with the model. This analysis thus provides a test of the PCAC hypothesis in the antineutrino energy range 5-150 GeV. © 1986 Springer-Verlag., 0, 42 auteurs, SCOPUS: ar.j, info:eu-repo/semantics/published

Evidence for a significant higher twist contribution to high z π- production in antineutrino scattering is presented. In events with W>3 GeV and Q2>1 GeV2 in our data, it accounts for (51 ±8)% of all π- with z above 0.5. It is consistent with the z-Q2 correlations of Berger's higher twist prediction. The data are inconclusive concerning the predicted y-z correlation and pT dependence. The z -Q2 correlation is not adequately described by the Lund Monte-Carlo. © 1986 Springer-Verlag., SCOPUS: ar.j, info:eu-repo/semantics/published

Coherent production of ρ- mesons in charged current antineutrino interactions on neon nuclei is studied in the BEBC bubble chamber exposed to the CERN SPS wide band beam. The cross section is measured to be (95±25)·10-40 cm2 per neon nucleus, averaged over the beam energy spectrum. The distributions of kinematical variables and the absolute value of the cross section are in agreement with theoretical predictions based on the CVC hypothesis and the vector meson dominance model. © 1987 Springer-Verlag.