E. Malamud

Production of jets and single particles at high p⊥ in 200 GeV hadron-beryllium collisions

Abstract We present results from an experiment studying the production of single particles and jets (groups of particles) with high p ⊥ (transverse momentum) in 200 GeV/ c interactions on a beryllium target. We give a detailed discussion of the ambiguities in the jet definition. The jet and single-particle cross sections have a similar shape but the jet cross section is over two orders of magnitude larger. The events show evidence for the coplanar structure suggested by constituent models, and the momentum distributions of charged particles give strong support to a simple quark-quark scattering model.

Proton-proton diffraction dissociation at incident energies from 175 to 400 GEV

Abstract Differential cross sections d 2 σ d t d M X 2 are presented for the inclusive reaction p + p → X in the range 0.01 t c ) 2 , 1.3 m X 2 2 , and incident energies from 175 to 400 GeV. The results are compared with data in the 20 GeV energy region.

Evidence for the Goldhaber effect in pp interactions at 300 GeV/c☆

Abstract We have observed evidence for the Goldhaber effect among pion pairs produced in six- and eight-prong events in pp interactions at 300 GeV/ c . We observe a pronounced difference between the opening angle distributions for pairs of pions of like and unlike electric charge. This effect decreases rapidly with increasing all-charged pion mass. Calculations indicate that resonance production can account for only about 30% of the observed effect. A search for the Goldhaber effect in high-charged-multiplicity events ( n c ⩾ 20) gives only inconclusive results.

Study of ϱ0 production in high multiplicity pp interactions at 300 GeV/c☆

Abstract We have searched for ϱ 0 production in 85 high multiplicity events with 18 or more charged particles. We observe an enhancement at the ϱ 0 mass but with a considerably narrower width. If we ignore this narrow width, we measure the cross section for pp → ϱ 0 + n charged particles with n ⩾ 16 to be 1.81 ± 0.46 mb. The ratio between the number of ϱ 0, s and π −, s is observed to increase from 0.08 ± 0.04 for p T c to 0.88 ± 0.23 for p T > 0.6 GeV/ c .

Structure of events in 200 GeV interactions on hydrogen and aluminum targets in both soft and hard collisions

Abstract The qualitative predictions of quantum chromodynamics for high-energy hadron-nucleus scattering are expounded. Inclusive particle distributions from hadron interactions on proton and aluminum targets are compared to the theoretical expectations for both low and high transverse momentum ( p ⊥ ) scattering. In the latter case, we present data on the nuclear effects in the fragmentation of both the beam and scattered partons. At low p ⊥ , we show evidence for short-range correlations between the final particles produced in hadron-aluminum collisions.

Valence quark effects in beam remnants in high Et proton-proton collisions at s=27.4 GeV

Abstract Charged particle trajectories have been reconstructed in pp collisions with transverse energies ( E t ) ranging from 1 GeV to 20 GeV. Data were collected by triggering on E t in a highly segmented calorimeter with full azimuthal coverage. Minimum bias triggers were also used. Valence quark effects are known to appear at low E t in the differences between positive and negative particle multiplicities in the forward direction. We reproduce these known prominent effects at low E t , but find them not present in the collisions with large E t , disappearing by about E t =8 GeV . Furthermore, events with high planarity do not show a strong forward net flow of charge and disagree with the predictions of ISAJET. The results suggest that for the triggers studied, more than a single pair of proton constituents scatter at this energy.

Negative results of a search for alignment in high energy collisions

Abstract Using proton-proton interactions at 205 and 300 GeV/ c we have searched for an alignment of the produced particles due to high angular momentum in the primary collision. The negative results of this search are discussed.

Study of the coherent reaction K+d → K0π+d at 2 GeV/c☆

Abstract We have made a study of the coherent reaction K+d → K0π+d at 2 GeV/c, using data obtained in the Lawrence Berkeley Laboratory 25 inch bubble chamber. The cross section for this reaction is 324 ± 25 μb, after correction for invisible K0 decays. This reaction is dominated primarily by vector exchange. We determine the parameters of the ω trajectory to be αω = (0.33 ± 0.04) + t.