Limit on the d¯/u¯ asymmetry of the nucleon sea from Drell-Yan production

We present an analysis of 800-GeV proton-induced Drell-Yan production data from isoscalar targets ${}_{}{}^2{}_{}{}^{}\mathrm{H}$ and C, and from W, which has a large neutron excess. The ratio of cross sections per nucleon, R-${\mathrm{\sigma }}_{\mathrm{W}}$/${\mathrm{\sigma }}_{\mathrm{IS}}$, is sensitive to the difference between the d¯(x) and u¯(x) structure functions of the proton. We find that R is close to unity in the range 0.04≤x≤0.27, allowing upper limits to be set on the d¯-u¯ asymmetry. Additionally, the shape of the differential cross section ${\mathit{m}}^3$ ${\mathit{d}}^2$σ/${\mathit{dx}}_{\mathit{F}}$ dm for ${}_{}{}^2{}_{}{}^{}\mathrm{H}$ at ${\mathit{x}}_{\mathit{F}}$≊0 shows no evidence of an asymmetric sea in the proton. We examine the implications of these data for various models of the violation of the Gottfried sum rule in deep-inelastic lepton scattering.