J. Solomon

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.

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.

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.

Hadroproduction of χc states in 530 GeV/c π− interactions with nuclear targets

We are studying production of χc states in 530 GeV/c π− interactions with several targets. χc mesons are observed in the mode (χ→J/ψ+γ). Only photons that converted to e+e− pairs are used in the reconstruction of the χc mesons. Preliminary analysis shows that the fraction of observed J/ψs coming from χc radiative decays is 0.44±0.09±0.08, and that the relative production rate of χc1 to χc2 is 1.3±0.6.

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.

Production ofJ/ψmesons inpBecollisions at 530 and800GeV/c

We report on the production of J/psi mesons in 530 and 800 GeV/c proton - Be collisions in the Feynman-x range 0.0 < xf < 0.6. The J/psi mesons were detected via decays into opposite sign muon pairs. Differential distributions for J/psi production have been measured as functions of xf, pT^2, and cosine of the Gottfried-Jackson decay angle. These distributions are compared with results on J/psi production obtained in 515 GeV/c pion - Be collisions, measured by the same experiment, as well as with results from other experiments using incident protons.

Production of

We report on the production of J/psi mesons in 530 and 800 GeV/c proton - Be collisions in the Feynman-x range 0.0 < xf < 0.6. The J/psi mesons were detected via decays into opposite sign muon pairs. Differential distributions for J/psi production have been measured as functions of xf, pT^2, and cosine of the Gottfried-Jackson decay angle. These distributions are compared with results on J/psi production obtained in 515 GeV/c pion - Be collisions, measured by the same experiment, as well as with results from other experiments using incident protons.

J/\psi

The E672/E706 Spectrometer, located in the MW beam at Fermilab, was used to collect data on events containing a pair of muons in the final state with large effective mass. The momentum of incident pions and protons was 530 GeV/c. Nuclear targets included Be, C, Al, Cu and Pb. We report on a preliminary measurement of the A‐dependence of the per nucleus cross section for forward J/ψ production. The apparatus also detected charged particles and γ’s produced in association with the muon pair. The expected physics results on the hadroproduction of χ states and beauty particles are discussed.

mesons in

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.