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

The Fermilab E866/NuSea Collaboration has measured the Drell-Yan dimuon cross sections in 800 GeV/c proton-proton and proton-deuterium collisions. This is the first measurement of the absolute Drell-Yan cross section in proton-proton collisions over a broad kinematic region and the most extensive study to date of the Drell-Yan cross section in proton-deuterium collisions. The Drell-Yan mechanism is sensitive to both the beam and target parton distributions. In particular, with the kinematics of the E866/NuSea data, the Drell-Yan mechanism is sensitive to the target antiquark distributions at low and intermediate Bjorken-x and to the beam quark distributions at high-x. Approximately 55K proton-proton and 121K proton-deuterium Drell-Yan events over the longitudinal momentum fraction (Feynman-x) range -0.05 < xF < 0.8 and the mass ranges 4.2 < Mμ+μ- < 8.7 GeV and 10.85 < M < 16.85 GeV are included. The data analysis will be described, and the doubly-differential M3d2σ/dMdxF, and triply-differential cross sections Ed3σ/dp3 will be presented. These results will be compared with previous measurements by E605 and E772 and to predictions based upon next-to-leading order calculations utilizing the MRST2001 and CTEQ6 global parton distribution function fits. The results indicate that recent global parton distribution fits provide a good description of the light antiquark sea in the nucleon over the Bjorken-x range 0.03 < x < 0.15. In contrast, the valence quark distributions appear to be overestimated by the current parton distribution fits as x → 1; a region in which, prior to this data, there was very little proton data to constrain the global fits. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]