J. C. Webb

Measurement of J / psi and psi-prime suppression in p-A collisions at 800-GeV/c

Measurements of the suppression of the yield per nucleon of J/psi and psi() production for 800 GeV/ c protons incident on heavy nuclear targets, relative to light nuclear targets, have been made with very broad coverage in x(F) and p(T). The observed suppression is smallest at x(F) values of 0.25 and below, and increases at larger values of x(F). It is also strongest at small p(T). Substantial differences between psi() and J/psi production are observed for the first time in p-A collisions. The suppression for psi() production is stronger than that for J/psi for x(F) near zero, but becomes comparable to that for J/psi for x(F)>0.6.

Parton Energy Loss Limits and Shadowing in Drell-Yan Dimuon Production

A precise measurement of the ratios of the Drell-Yan cross section per nucleon for an 800 GeV/{ital c} proton beam incident on Be, Fe, and W targets is reported. The behavior of the Drell-Yan ratios at small target-parton momentum fraction is well described by an existing fit to the shadowing observed in deep-inelastic scattering. The cross-section ratios as a function of the incident-parton momentum fraction set tight limits on the energy loss of quarks passing through a cold nucleus. {copyright} {ital 1999} {ital The American Physical Society}

Measurement of Angular Distributions of Drell-Yan Dimuons in p + d Interaction at 800 GeV/c

We report a measurement of the angular distributions of Drell-Yan dimuons produced using an 800 GeV/c proton beam on a deuterium target. The muon angular distributions in the dilepton rest frame have been measured over the kinematic range 4.5<m{mu mu}<15 GeV/c{2}, 0<p{T}<4 GeV/c, and 0<x{F}<0.8. No significant cos2phi dependence is found in these proton-induced Drell-Yan data, in contrast with the situation for pion-induced Drell-Yan data. The data are compared with expectations from models which attribute the cos2phi distribution to a QCD vacuum effect or to the presence of the transverse-momentum-dependent Boer-Mulders structure function h{1}{perpendicular}. Constraints on the magnitude of the sea-quark h{1}{perpendicular} structure functions are obtained.

Improved measurement of the anti-d / anti-u asymmetry in the nucleon sea

Measurements of the ratio of Drell-Yan yields from an 800 rm{GeV/c} proton beam incident on liquid hydrogen and deuterium targets are reported. Approximately 360,000 Drell-Yan muon pairs remained after all cuts on the data. From these data, the ratio of anti-down (

Measurement of Upsilon production for p + p and p + d interactions at 800 GeV/c.

bar{d}

J/psi polarization in 800-GeV p-Cu interactions.

) to anti-up (

d̄/ū asymmetry and the origin of the nucleon sea

bar{u}

Anti-d / anti-u asymmetry and the origin of the nucleon sea

) quark distributions in the proton sea is determined over a wide range in Bjorken-

Measurement of the Absolute Drell‐Yan Dimuon Cross Section in 800 GeV/c Proton‐Proton and Proton‐Deuterium Collisions

x

{bar d}/{bar u} asymmetry and the origin of the nucleon sea

. These results confirm previous measurements by E866 and extend them to lower