Search

Evidence of the production of the Ds∗-(2111) meson in v μ Ne collisions is presented. The Ds∗- production rates the Ds−→φπ− branching fraction is estimated to be (2.3±0.7) × 10−3 of all charged currents having a hadronic mass W above 3 GeV.

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 first observation of μ + e + events produced in antineutrino interactions using the Fermilab 15 ft bubble chamber is reported. The relative yield of μ + e + events is (4.8 −3.2 +5.3 ) × 10 −4 of all charged-current events with antineutrino energy greater than 10 GeV. The observed V 0 rate is 1.0 −1.0 +1.2 per μ + e + event. Possible sources of these events are discussed.

Charmed strange meson neutrinoproduction is investigated. TheD s − (1970) antineutrino production rate is measured. Two higher $$(\bar cs)$$ states are seen in the decay channels γD * (2110) andD *K, respectively.

The cross section of the quasi-elastic reactions $$\bar v_\mu p \to \mu ^ + \Lambda (\Sigma ^0 )$$ in the energy range 5–100 GeV is determined from Fermilab 15′ bubble chamber antineutrino data. TheQ 2 analysis of quasi-elastic Λ events yieldsM A=1.0±0.3 GeV/c2 for the axial mass value. With zero µΛ K 0 events observed, the 90% confidence level upper limit $$\sigma (\bar v_\mu p \to \mu ^ + \Lambda {\rm K}^0 )< 2.0 \cdot 10^{ - 40} cm^2 $$ is obtained. At the same time, we found that the cross section of reaction $$\bar v_\mu p \to \mu ^ + \Lambda {\rm K}^0 + m\pi ^0 $$ is equal to $$\left( {3.9\begin{array}{*{20}c} { + 1.6} \\ { - 1.3} \\ \end{array} } \right) \cdot 10^{ - 40} cm^2 $$ .

Evidence is reported for F ∗− antineutrino production with the subsequent radiative decay F ∗− → γ F − . We find 143±18 MeV for the F ∗ − F mass difference.

The study of neutral strange particle production in antineutrino-induced neutral current interactions is presented. The total multiplicity of neutral strange particles and the K 0 multiplicity in the current fragmentation region ( z >0.3) are used to estimate in two ways the coupling strength of the weak neutral current to the strange quark.

The total v μ N charged current cross section in the energy interval 10–50 GeV is unfolded from 15' bubble chamber antineutrino data. The method is to isolate the quasielastic events and determine their relative contribution to the overall charged current sample. The scale parameter is found to be (0.29 ± 0.03) × 10−38 cm2 GeV−1. Relevance of the method for neutrino oscillation studies is discussed.

The two-stage decay D ∗− → D 0 π − , D 0 → K + π − X of the D ∗− mesons produced by antineutrinos in the 15 ft bubble chamber is studied. For an antineutrino energy above 10 GeV the rate of D ∗− production relative to all charged current events is found to be 0.042 ± 0.013.

A search is performed for the antineutrino oscillation process ν μ → ν τ with 15' bubble chamber data. Assuming maximal mixing, we obtain for the neutrino mass difference parameter Δ 16 eV2 the transition probability is found to be less than 0.022 (90% c.1.).