We report a high statistics measurement of Υ production with an 800GeV/c proton beam on hydrogen and deuterium targets. The dominance of the gluon-gluon fusion process for Υ production at this energy implies that the cross section ratio, σ(p+d→Υ)/2σ(p+p→Υ), is sensitive to the gluon content in the neutron relative to that in the proton. Over the kinematic region 0<xF<0.6, this ratio is found to be consistent with unity, in striking contrast to the behavior of the Drell-Yan cross section ratio σ(p+d)DY/2σ(p+p)DY. This result shows that the gluon distributions in the proton and neutron are very similar. The Υ production cross sections are also compared with the p+d and p+Cu cross sections from earlier measurements.
ASJC Scopus subject areas
- Physics and Astronomy(all)