Backward particle production in neutrino neon interactions

Backward proton and pion production is studied in ν and \(\bar v\) 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.     

Coherent single pion production by antineutrino charged current interactions and test of PCAC

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 \(\bar v_\mu \) 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, theQ ² dependence is well described by a propagator containing a massm=(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.     

Diffractive production of ρ-mesons and of ρπ-systems by neutrinos and antineutrinos on protons

Evidence is presented for diffractive production of -mesons and of -systems invp and chargedcurrent interactions. In the (anti-)neutrino energy range 10 GeVE _v <60 gev=" the=" cross=" sections=" for=" diffractive="> and diffractive production are found to be (0.64±0.14 (stat.)±0.08 (syst.))% and (0.28±0.08 (stat.)±0.04 (syst.))% of the charged-current cross section. The diffractive signal is consistent with being entirely due to diffractivea ₁ production. However, the data cannot distinguish between diffractivea ₁ and diffractive nonresonant production. The experimental distributions ofW, Q ²,x _Bj andy _Bj for diffractive and events are consistent with model predictions.     

Diffractive production of charmed strange mesons by neutrinos and antineutrinos

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.     

Inclusivef 2 (1270) meson production in νp and\bar vp charged current interactions

Using data obtained with the bubble chamber BEBC at CERN, the inclusivef ₂ (1270) meson production invp and \(\bar vp\) charged current reactions is studied. It is found thatf ₂ production occurs mainly in events with a hadronic invariant massW?7 GeV. In these events, the averagef ₂ multiplicity is about half the average ρ^O multiplicity, and thex _F andp _T ² distributions of thef ₂ agree in shape with those of the ρ^O. 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 largef ₂ multiplicities.     

A measurement of the proton structure functions from neutrino-hydrogen and antineutrino-hydrogen charged-current interactions

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 ratiod _v /u _v 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.     

Determination of the ratior v =d v u v of the valence quark distributions in the proton from neutrino and antineutrino reactions on hydrogen and deuterium

Zeitschrift für Physik C Particles and Fields - A set of proton longitudinal polarized distributions, worked out under the assumption of small gluon polarization, is used to evaluate several...     

Multiplicities of secondary hadrons produced in vp and vp charged current interactions

In an experiment with the hydrogen bubble chamber BEBC at CERN multiplicities of hadrons produced in νp and $\text{v}\text{p}$ interactions have been investigated. Results are presented on the multiplicities of charged hadrons and neutral pions, forward and backward multiplicities of charged hadrons and correlations between forward and backward multiplicities. Comparisons are made with hadronic reactions and e⁺e^? annihilation. In the framework of the quark-parton model the data imply similar charged multiplicities for the fragments of a u- and a d-quark, and a larger multiplicities for the fragments of a uu- than for a ud-diquark. The correlation data suggest independent fragmentation of the quark and diquark for hadronic masses above ～ 7 GeV and local charge compensation within an event.     

Study of transverse momenta of charged hadrons produced in νp and\bar vp charged current interactions

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 1^st order QCD (hard gluon emission) are negligible.