Results from a high-statistics experiment involving an exposure of the SLAC 82-in. hydrogen bubble chamber to a beam of 8-GeV/c ${\ensuremath{\pi}}^{\ensuremath{-}}$ yielding a final state of ${\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}p$ are presented. Copious production of $\ensuremath{\rho}$, ${\ensuremath{\Delta}}^{++}$, and $f$ is found. Considerable quasi-two-body production in which one particle decays to one of the above resonances is also observed. Some double-resonance production involving baryon and meson resonances is also seen. The production properties of $\ensuremath{\rho}$, ${\ensuremath{\Delta}}^{++}$, and $f$ mesons are well described by a double-Regge model.

From a study of 8-GeV/c π−p interactions, the various two-pion and four-pion decay channels available to the g− meson have been investigated. Our results indicate that the dominant 4π decay modes involve intermediate ρ and ω production without significant A2 formation.Received 13 April 1982DOI:https://doi.org/10.1103/PhysRevD.26.2183©1982 American Physical Society

Results of a high-statistics study of elastic scattering and meson resonances produced by π−p interactions at 8 GeV/c are presented. Large statistics and small systematic errors permit examination of the complete kinematic region. Total differential cross sections are given for ρ0,−, f0, g0,−, Δ±, Δ0, and N* resonances. Spin-density matrix elements and Legendre-polynomial moments are given for ρ, f, and Δ resonances. The results for ρ0 and f0 resonances are compared with the predictions of a Regge-pole-exchange model. Properties of the above resonances are compared and discussed. In particular, we present evidence that the ρ0 and f0 production mechanisms are similar. The similarity of the g0 t distribution to that of the ρ0 and f0 suggests a common production mechanism for all three resonances.Received 11 January 1982DOI:https://doi.org/10.1103/PhysRevD.26.1572©1982 American Physical Society

We investigate properties of the hadron jets produced in deep inelastic antineutrino-nucleon charged current interactions in the Fermilab 15 foot bubble chamber. Our detailed analysis of the jet net charge provides evidence for the quark origin of the hadron jets. The factorization hypothesis for the inclusive one-particle cross section is found to be valid.

We have studied inclusive ${\ensuremath{\rho}}^{0}$ and ${\ensuremath{\Delta}}^{++}$ production in ${\ensuremath{\pi}}^{+}p$ and ${\ensuremath{\pi}}^{\ensuremath{-}}p$ interactions at 15 GeV/c in a region where pion exchange has been found to dominate the resonance production. By using ${\ensuremath{\rho}}^{0}$ production, the off-mass-shell interactions of virtual pions with the target protons have been studied and compared with the same on-shell reactions at comparable energy. No significant differences between on-shell and off-shell reactions have been found in topological-cross-section ratios, inclusive longitudinal- or transverse-momentum distributions, or elastic $\frac{d\ensuremath{\sigma}}{\mathrm{dt}}$ distributions. The effect of the negative mass squared of the virtual pions has also been studied. Inclusive ${\ensuremath{\Delta}}^{++}$ production has been found to be dominated by pion exchange for $|t|\ensuremath{\lesssim}0.4$ (${\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{2}$. We have studied the interactions of these off-shell pions with the beam pions as a function of energy. The ratio $\frac{{\ensuremath{\sigma}}_{\mathrm{el}}}{{\ensuremath{\sigma}}_{T}}$ and the average charged-particle multiplicities $〈{n}_{X}〉$ have been examined and compared with those for various hadron-proton reactions. The values of $〈{n}_{X}〉$ have also been studied in terms of a simple model and found to give results consistent with studies at higher energies. We also present longitudinal- and transverse-momentum distributions for produced pions, as well as $\frac{d\ensuremath{\sigma}}{\mathrm{dt}}$ distributions for $\ensuremath{\pi}\ensuremath{\pi}$ elastic scattering.

We have studied transverse momenta of charged hadrons in the current fragmentation region of charged current antineutrino- nucleon interactions observed in the Fermilab 15 ft bubble chamber. The measured momentum squared transverse to the vμ+ plane (pout2) of the negative hadrons varies as a function of Q2, W2 and x as expected from t he leading order perturbative QCD calculations. Positively charged hadrons show a different transverse momentum behaviour as a function of Q2.

In this paper we discuss inclusive spectra of K0's and Λ's produced in charged in charged-current νμN interactions in the Fermilab 15 ft bubble chamber filled with a 64% Ne-H2 mixture. Data presented in terms of the invariant cross section show, when compared with results from experiments with other incident beams, that the behavior of these distributions is approximately the same. The K0 and Λ fragmentation functions are presented and the shape of the K0 fragmentation function is found to be consistent with the parametrization of Field and Feynman.

The results of a study of strange particle production in charged current νμN interactions in the Fermilab 15 ft bubble chamber filled with a heavy NeH2 mixture are presented. Production rates and average multiplicities of K0's and Λ's as functions of W2 and Q2 are given. The experimental data agree well with the quark-parton model predictions if a yield of 0.06 ± 0.02 of K0's and Λ's from charm production is included. Upper limits for D-meson production are given and the shape of the charmed quark fragmentation function is discussed. Inclusive production of the K∗(890) and Σ(1385) resonances is measured and it is shown that only about 5% of the K0 mesons and Λ hyperons results from resonance decays. Relative production rates of neutral strange particles on proton and neutron targets are studied.

Backward protons from neutrino and antineutrino interactions in a Ne-${\mathrm{H}}_{2}$ mixture are studied. The inclusive characteristics of the reactions are presented for both neutral- and charged-current events and comparison with models are made. The data are in agreement with the hypothesis of nuclear scaling.

Diffraction dissociation of both the beam and target particles has been observed in 150-GeV/c π−p interactions in the Fermilab 30-in.-bubble-chamber-proportional-wire-chamber hybrid spectrometer. The dissociations are observed as recoil systems opposite leading particles, the signals of which are separated from background where appropriate by a variant of the Van Hove sector cut, thus allowing the high-mass portion of the spectrum to be observed. Pion dissociation has a cross section of 1758±105 μb, divided among two-, four-, and six-prong events; some ρ0 production is seen and comes primarily from the π−→2π−π+ channel. The proton dissociation cross section is 1726±100 μb, again divided among two-, four-, and six-prong events. The final state contains a neutron more frequently than a proton in the two-and six-prong events, a proton more frequently in the four-prong events. Production of Δ++ is observed in the p→pπ+π− dissociations.Received 15 March 1979DOI:https://doi.org/10.1103/PhysRevD.21.1726©1980 American Physical Society

We have used the ratio between the production rates of K0's and π−'s in antineutrino-nucleon interactions in the Fermilab 15 ft bubble chamber to measure the size of the SU (3) symmetry violation in the production of quark-antiquark pairs to be 0.27±0.04. This value is significantly larger than the value obtained from a recent ep experiment. There is no apparent dependence of the K0π− ratio with W2, Q2, xb or pT2.