R. Abrams

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.

A study of the reaction π−p → π+π−n at 100 and 175 GeV/c

Abstract The reaction π−p → π+π−n was studied at 100 and 175 GeV/c incident beam momenta. The ϱ0 region cross section was 0.934 μb at 100 GeV/c and 0.229 μb at 175 GeV/c. Spherical harmonic moments in the Gottfried-Jackson frame are presented as a function of mass and proton-neutron four-momentum transfer. The pion Regge trajectory is calculated. Decay distributions are presented for the ϱ in the helicity and Gottfried-Jackson frames. The apparatus and analysis are discussed.

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.

Scaling and fragmentation distributions of beam remnants in high Et proton-proton collisions at √s =27.4 GeV

Abstract Charged particle trajectories have been reconstructed in pp collisions triggered by transverse energies ( E t ) ranging from 1 GeV to 20 GeV. The forward fragmentation function of negative particles in the beam jet is found to scale with E t in variable x =2 p L /√ s − E t , and the slope is near to that found for small jet triggers in an earlier experiment. Above about E t =8 GeV, positive particles scale and for 0.5 x E t do not show the behavior expected from the fragmentation of diquarks and are more like that from quarks. Multiplicity and energy flow in various forward polar angle regions are also presented; they are compared to the beam jet predictions of ISAJET and found to be greater at wide angles and less at small.

D and E mesons and possible KKK enhancements

Results are presented from the study of multikaon final states in the reactions r−p→K0K±r∓X, K0K+KX at 50 and 100 GeV/c. Here X is semi‐inclusive, because a specific forward topology and an interaction registering in the counters sourrounding the target are required. The D(1285) meson is seen in the dr mode, while the E(1420) meson is observed in both the dr and the KK modes. In addition, there are two possible enhancements in the three kaon final state. The first (M∠1840 MeV) is associated with the K0f mode and is consistent with being the charmed D0. The second, a K state (M = 2003±14 MeV, G = 87±43 MeV), decays into KA2.

Study of K * − ( 890 ) and K * − ( 1430 ) production in the reaction K − p → K ¯ 0 π − p at 100 and 175 GeV/ c

The reaction K/sup -/p..-->..K/sup 0/..pi../sup -/p has been studied at 100 and 175 GeV/c and the reaction ..pi../sup -/p..-->..K/sup 0/K/sup -/p at 50, 100, and 175 GeV/c. Both reactions are dominated by production of resonances, K((890), K((1430) and A/sub 2/(1320), A/sub 2/(2040), respectively. Production cross sections, t distributions, and decay-angular distributions are studied. Isoscalar natural-parity exchange is dominant. The energy dependence of the K( and A/sub 2/ resonance production between 10 and 175 GeV/c is well described by a Regge-pole model. Our data on A/sub 2/ corrects that in an earlier paper.

Study of K/sup -/(890) and K/sup -/(1430) production in the reaction K/sup -/p. -->. K/sup 0/. pi. /sup -/p at 100 and 175 GeV/c

The reaction K/sup -/p..-->..K/sup 0/..pi../sup -/p has been studied at 100 and 175 GeV/c and the reaction ..pi../sup -/p..-->..K/sup 0/K/sup -/p at 50, 100, and 175 GeV/c. Both reactions are dominated by production of resonances, K((890), K((1430) and A/sub 2/(1320), A/sub 2/(2040), respectively. Production cross sections, t distributions, and decay-angular distributions are studied. Isoscalar natural-parity exchange is dominant. The energy dependence of the K( and A/sub 2/ resonance production between 10 and 175 GeV/c is well described by a Regge-pole model. Our data on A/sub 2/ corrects that in an earlier paper.