Search

A significant intermittency signal is observed in 630 GeV p p collisions measured in the UA1 central detector. It occurs with similar magnitude in different variables: pseudorapidity, rapidity and azimuthal angle. The signal increases with decreasing charged particle multiplicity in the event. Its strength in a sample of low p⊥ tracks and its multiplicity dependence are not reproduced by commonly used Monte Carlo models of high energy interactions.

Channeling phenomena are observed for positive particles of momentum up to 250 GeV/ c in a germanium crystal. The polar angular distributions of the channeled particles are compared with theoretical predictions based on a diffusion model. The results indicate that at high particle energy there may be additional mechanisms besides those operative at low energy leading to dechanneling of the particles. In spite of this, channeling effects are observed for particles incident at up to several times the critical angle, in contrast with the results from low energy channeling. Statistical equilibrium in the azimuthal angular distribution has also been observed at all measured beam momenta to about twice the calculated channeling critical angle. The breakdown of statistical equilibrium for the 2 cm crystal used occurs at an incident angle 2–3 times smaller than predicted theoretically.

Channeling of protons and positive and negative pions has been observed in a single crystal of germanium at beam momenta of 35, 100 and 250 GeV/c. Both energy loss and scattering have been measured. The channeling effects agree with observations at lower energies suitably scaled to these high energies. The suppression of inelastic nuclear interactions has been directly observed by monitoring multiple-track events.

The charge asymmetry in the decay η′(958)→π+π−γ has been measured using η′ mesons produced in the reaction π−p→η′n at 2.1 GeV/c incident pion momentum. A value for the asymmetry of (−6.9±7.8%) was obtained, based on 295±31 events after background subtraction. This result is consistent with C invariance in this decay.

Final states produced by charged baryon exchange in π−p interactions at 12 GeV/c laboratory momentum have been studied. Forward neutrons with momenta determined by a calorimeter to be greater than 8.5 ± 1.4 GeV/c triggered the SLAC 40-inch hydrogen bubble chamber which operated at a 10 Hz expansion rate. We report data on the reactions π−p→nπ−π+, π−p→nπ−π+π0, and π−p→nπ−π−π+π+. In π−nπ−p→nπ+, production of ϱ and f mesons is observed. Differential cross sections are derived and compared with data at lower incident momentum and with theoretical models. In π−p→nπ−π+π0, ω production is observed with a differential cross section having a deep near u′= 0.2 (GeV/c)2. In π−p→nπ−π−π+π+, Δ−, ϱ and f production is observed . The observed mass distributions appear to indicate the production of wide resonaces decaying into ϱππ. Some evidence for ϱ-ω interference is also observed.

Data are presented for the reactions K+p → Λpp and K+p → ΛK+K+ at 7.3 GeV/c. A satisfactory parameterization of these processes is obtained using the double-Regge phenomenology. The data are also compared with predictions of a spin-independent, generalized Veneziano model.

New data for the reaction K−p → ΛK+K− at 3.3 GeV/c have been used to investigate the five-particle generalized Veneziano model. The amplitude is constrained by symmetry properties of the crossed channels and by non-exchange degeneracy of the Nα∗ trajectory. The Harari-Rosner dual quark model determines the trajectories which couple to the K+K− system. Reasonable choices for the other trajectories lead to good agreement with these data as well as data at higher and lower beam momentum. The pomeron exchange contribution to the reaction is shown to be small; however, both pseudoscalar and vector kinematic factors are required for detailed agreement with the angular distributions. The model fails to account for the crossing-symmetric reaction K+p → ΛK+K+.