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In a bubble chamber experiment with BEBC the spin alignment parameter η= 1 2 (2ϱ 00 − ϱ 11 − ϱ −1−1 ) is measured for ϱ0 mesons produced in deep inelastic charged-current antineutrino and neutrono interactions on neon. In the current fragmentation region η is found to be η v =0.48±0.27 ( stat. )±0.15 ( syst. ) for v Ne and ηv=0.12±0.20 (stat.)±0.10 (syst.) for vNe interactions

Four data sets of charged current neutrino and antineutrino interactions with neon, deuterium and hydrogen collected from BEBC and the 15 Foot Bubble Chamber are used to study the Bose-Einstein correlations between like-sign charged pions. Two forms of the parametrization for the effect are used. No substantial differences are found between the data sets obtained with neon, deuterium and hydrogen targets. The Lorentz invariant parametrization of Goldhaber gives for the radius of the pion emission region the valuer G =0.80 ±0.04±0.16 fm and for the chaoticity parameter the value ψ=0.61±0.04±0.15. Using the Kopylov-Podgoretskii parametrization yieldsr K =1.27±0.06±0.12 fm, ψ=0.58±0.03±0.12 and for the pion source lifetimec τ=0.52±0.05±0.12 fm. The Goldhaber parametrization was used to study the effect in further detail. The same emission radius and the same strength of the effect were found for particles produced in interactions on neutrons and protons. The data are compatible with a spherical shape of the pion emission region. No multiplicity or forward-backward dependences are found. No dependence of the effect on the event kinematical variables is seen.

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.

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

A study is presented of the inclusive production cross sections of K∗±(892) vector mesons in pp interactions at 12 and 24 GeV/c and in π+p interactions at 16 GeV/c. The K∗± inclusive cross section is ∼0.9 mb for both pp at 24 GeV/c and π+p interactions at 16 GeV/c. For pp interactions, σ(K∗+) and σ(K∗−) are seen to rise with energy, showing a threshold behaviour. In both pp and π+p interactions, σ(K∗+) largely exceeds σ(K∗−) at these energies and this excess is interpreted as K∗+ production by beam and target fragmentations. The decays of K∗±0 yield ∼30% of the K0 observed in the final states. The pT2 dependence of both K∗+ and K∗− cross sections is described by an exponential with slope of ∼3.3 (GeV/c)−2. The longitudinal momentum spectra for K∗+ in 16 GeV/c π+p and 24 GeV/c pp interactions are similar in shape in the target hemisphere. The K∗− spectra are similar over the whole kinematic region when viewed in the quark c.m.s. and point to a central production mechanism. Comparing K∗+ and ρ0 production, striking similarities are found.

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

The production of ρ0(770) and f(1270) is studied in π−p interactions at 16 GeV/c. By comparison with inclusive K∗0 production in the reaction K−p → K∗0 + anything, and with inclusive ρ0 production in the reaction pp → ρ0 + anything, it is found that the data can be interpreted in terms of two production processes: the central production of resonances and the fragmentation of the beam particle. For the π−p reaction, the inclusive ρ0 beam fragmentation cross section is 3.1 ± 0.3 mb while that for central production is 1.6 ± 0.5 mb. The ρ0 central production cross section is consistent with increasing with energy as ln s behaviour. The ratio of ρ0 to π− inclusive cross sections (excluding the leading π−) is ∼0.2, independent of energy. The ρ0 to π− ratio increases as a function of pT to a constant value of ∼12 above 1 GeV/c. The ρ (charged and neutral) and f decays account for (25 ± 4)% and (1.4 ± 0.3)%, respectively, of all pions produced.

The coherent production of π+ mesons by charged current neutrino interactions on neon nuclei in BEBC is compared to the predictions of the PCAC hypothesis and the meson dominance model. Good agreement is observed. © 1989 Springer-Verlag.

Total and differential cross sections ofK*−(890),K*−(890),\(\bar K^{ * 0} \)(890),K*0(890),\(\bar K^{ * 0} \)(1430) andϱ0(770) produced inK−p interactions at 110 GeV/c are presented. The cross sections of the neutral resonances show a smooth increase with energy from 10 to 110 GeV/c incident momentum. For theK*+(890) and theK*0(890), i.e. the resonances with strangenessS=+1, this rise is quite significant: their cross sections practically double between 32 GeV/c and 110 GeV/c incidentK− momentum. About 50% of the neutral kaons and 30% of charged pions produced inK−p interactions at our energy are found to be decay products of the resonances considered.

Comparing the kinematical distributions of events obtained on neon and deuterium targets in similar experimental conditions reveals a reduction of the neutrino and antineutrino charged current cross section per nucleon in neon at low Q 2 . The effect, interpreted as due to geometric shadowing of the weak propagator in interactions of neutrinos and antineutrinos with nuclei, agrees well with predictions derived from PCAC.

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

Second-order interference of pion pairs of equal charge is observed in good statistics samples of 16 GeV/c π+p and K−p interactions (2 × 106 and 106 pion pair combinations, respectively) and in a smaller sample of p p annihilations at rest. The effective radius R of the pion source is found to be approximately 1.4 fm for all three types of interaction. The interference does not appear to be “total”, about 60–80% of the like pairs interfering. It is shown that the numerical results for the radius R, for the depth cτ of the source “photosphere” and for the fraction λ of the interfering pairs are sensitive to any dynamical correlation in the background, and hence depend on the background chosen. It is argued that further refinements in the theoretical formulation of the phenomenon and in the experimental approach are needed for truly quantitative results.

Multiplicity distributions and correlations between charged particles in the forward and back-ward c.m. hemispheres are studied inK −p interactions at 110 GeV/c and compared with other data on mesonnucleon scattering. The interpretation in terms of a simple quark-parton picture assuming that the forward multiplicity is dominated by quark fragmentation and the backward multiplicity by diquark fragmentation is supported by the experimental fact that the forward and the backward mean multiplicities are approximately equal to half of thee + e − andpp multiplicities, respectively. The 110 GeV/cK −p data show significant correlations between the numbers of slow forward and slow backward particles, whereas the multiplicities of fast forward and fast backward particles are independent.

BEBC filled in turn with hydrogen, and with a neon-hydrogen mixture, was exposed to the CERN SPS wide band neutrino and antineutrino beams. The ratios of the charged-current cross sections per nucleon, σ(νH2) σ(νNe) and σ(νH2) σ(νNe), between 20 and 300 GeV were found to be 0.656 ± 0.020 and 1.425 ± 0.052, respectively. Multiplying these ratios by the revised cross sections in neon, σ(νNe) E = (0.723 ± 0.038) × 10-38 cm2/GeV per nucleon and σ(νNe) E = (0.351 ± 0.019) × 10-38 cm2/GeV per nucleon, and their ratio, σ(νNe) σ(νNe) = 0.485 ± 0.020, yields values for the total charged-current cross sections on protons, σ(νp)/E and σ(νp) E, of (0.474 ± 0.029) × 10-38 cm2/GeV and (0.500 ± 0.032) × 10-38 cm2/GeV. respectively, and a value for the ratio σ(νp) σ(νp) of 1.053 ± 0.066. © 1986., 0, 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