We have measured the polarization of Λ's in inclusive pp and K−p reactions and of Λ¯'s in p¯p interactions at a beam momentum of 176 GeV/c. Data were taken in the beam-fragmentation region with hyperon transverse momenta from 0.2 to 1.5 GeV/c. The P¯ produced Λ¯'s have the same magnitude and sign of polarization as the p-produced Λ's, whereas the Λ's from K−p interactions are more highly polarized and in the opposite direction.
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A study of the inclusive and semi-inclusive Λ and Λ production in K + p interactions at 32 GeV/ c is presented. The inclusive cross sections for Λ and Λ amount to 0.78 ± 0.05 and 0.42 ± 0.04 mb thus showing a remarkable growth between 16 and 32 GeV/ c with a factor of 1.7 for Λ and 2.8 for Λ . Target and beam fragmentation processes are found to be dominant for Λ and Λ production respectively with the following lower limits for the corresponding cross sections: σ(p → K + ʌ) > 0.5 mb and σ(K + → p ʌ ) > 0.3 mb . Although the early scaling conditions are fulfilled for the Λ production in the target fragmentation region, and Λ production in the beam fragmentation region, scaling is not observed between 16 and 32 GeV/ c in the x and p T 2 Feynman variables. The Λ production is found to be very similar in the K + p inclusive reaction at 32 GeV/ c and in the semi-inclusive reaction K − p → Λ K K X at the same energy. The Λ Λ pair production cross section increases significantly in K + p interactions from 16 to 32 GeV/ c where it reaches the value σ Λ Λ = 47 ± 11 μ b . The cross sections for Λ or Λ produced in association with an identified proton are also given and discussed.
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The reaction K + p→ Δ ++ (1236)+ anything is studied at beam momenta 8.2 and 16 GeV/ c and compared with other Δ ++ producing reactions. We find that the low-mass Δ ++ π − enhancement affects the shapes of Δ ++ inclusive distributions. The triple-Regge formula is found to be consistent with the data. Dual properties of this formula are successfully tested.
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We have studied the inclusive production of strange meson and baryon resonances in 360 GeV/cpp interactions. Cross sections forK*+(892) andK*−(892) are estimated to be 4.42±0.62 mb and 2.54±0.47 mb respectively and those for∑+(1385) and∑−(1385) are 0.67±0.11 mb and 0.26±0.07 mb respectively. Longitudinal and transverse momentum distributions forK*(892) and Σ(1385) are presented, as well as for their decay productsK0 and Λ. An estimation is given on theK*(1430) and∑*(1915) productions.
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The Fermilab 15-ft bubble chamber, filled with a heavy neon-hydrogen mix, was exposed to a narrow-band νμ beam. Based on the observation of 830 charged-current νμ interactions, the cross section was found consistent with a linear rise with the neutrino energy in the interval 10 GeV<~Eν≲240 GeV. The average slope was determined to be σνEν=(0.62±0.05)×10−38 cm2 GeV−1.
Measured charged current total cross section.
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The data on the total inelastic and partial cross sections in pNe interactions at 300 GeV are presented. It is found that the total cross section, σin(pNe)=356±13 mb, and multiplicity distributions of the number of negative and relativistic charged particles are in good agreement with predictions of a multiple-scattering model based on Glauber's approach. The multiplicity of negative particles obeys the Koba-Nielsen-Olesen (KNO) scaling, but it is observed that the KNO function depends on the atomic mass number of the target. From an analysis of the average multiplicities of secondary particles, it is shown that approximately 10 percent of the fast (p≳1.2 GeV) positive secondaries are protons, which are derived from the nucleons in the neon nucleus.
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The total cross sections for νμn and νμp charged-current interactions and their ratio R=σT(νn)σT(νp) have been measured as a function of neutrino energy from 0.4 to 10 GeV. The experiment is performed using the BNL 7-foot deuterium bubble chamber exposed to the Alternating Gradient Synchrotron wide-band neutrino beam. The absolute values of the cross sections are normalized to the quasielastic scattering (νμn→μ−p) cross section. Above 1.6 GeV the data are consistent with the quark-parton model. We find that σT(νn)Eν=(1.07±0.05)×10−38, σT(νp)Eν=(0.54±0.04)×10−38, and σT(νN)Eν=(0.80±0.03)×10−38 cm2/GeV for 〈Eν〉=3.2 GeV, and R=1.95±0.10 for 〈Eν〉=3.7 GeV.
Axis error includes +- 0.0/0.0 contribution (?////SYSTEMATIC ERROR NOT GIVENNEUTRAL CURRENT AND NEUTRAL PARTICLES INDUCED REACTIONS, RESCATTERING IN DEUTERIUM).
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The inclusive production of neutral kaons in 70 GeV/ c K + p interactions is studied with the CERN BEBC bubble chamber. The (semi-)inclusive cross sections are interpreted in terms of the various strangeness channels leading to neutral kaon production. The invariant inclusive cross section for kaon production is studied as a function of p t 2 and the Feynman variable x . The latter distributions are considered both “raw” and corrected for the presence of K 0 's resulting from K ∗ decay. They are compared with the predictions expected from the Regge-Mueller formalism, the recombination model and fragmentation models.
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A factorial moment analysis has been performed on the differential multiplicity distributions of hadronic final states of the Z 0 recorded with the OPAL detector at LEP. The moments of the one-dimensional rapidity and the two-dimensional rapidity versus azimuthal angle distributions are found to exhibit “intermittent” behaviour attributable to the jet structure of the events. The moments are reproduced by both parton shower and matrix element QCD based hadronisation models. No evidence for fluctuations beyond those attributable to jet structure is observed.
Corrected factorial moments of the rapidity distribution with respect to the sphericity axis. The errors shown are statistical only but include the statistical error onthe correction factor, added in quadrature.
Corrected factorial moments of the rapidity distribution with respect to the electron beam axis. The errors shown are statistical only but include the statistical error onthe correction factor, added in quadrature.
Corrected factorial moments of the rapidity (with respect to the sphericityaxis) versus PHI distribution. For each point the NUMBER of bins are constructe d from equal numbers of YRAP and PHI bins. The errors shown are statistical only but include the statistical error onthe correction factor, added in quadrature.
Results of the experimental study of inclusive φ meson production off berillium nuclei by 70 GeV/ c protons in the beam fragmentation region x > 0.41 are presented. Fitting of the measured differential cross sections to the forms d σ d x ∼ (1 − x) n x and d σ d p 2 t ∼ exp (−bp 2 t ) gives the parameters n = 6.0 ± 1.7 and b = (2.4 ± 0.7) (GeV/ c ) −2 . In the framework of a quark-parton model the measured φ meson x -distribution suggests that in the region of x > 0.41 nearly 90% of the φ mesons are produced via a strange sea quark fusion. The ratio of the OZI-forbidden and OZI-allowed transition coupling constants has been found to be ten times smaller than the same ratio calculated from the partial decay widths. The total inclusive cross section is estimated to be σ (pN → φ X) = (0.7 ± 0.2) × 10 −27 cm 2 .
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