Isolating the flavor-symmetry-breaking component of the nucleon sea from Drell-Yan asymmetries

Recent New Muon Collaboration measurements of $p-n$ asymmetries in $F_2$ structure functions through deep-inelastic muon scattering suggest possible SU(2)-flavor breaking in the nucleon sea. Ellis and Stirling showed that asymmetries in Drell-Yan processes for protons scattered from proton and deuteron targets could shed light on the sea and valence structure functions. We show that the relevant quantity $\overline{d}\mathrm{}\left(x\right)-\overline{u}\mathrm{}\left(x\right)\mathrm{}$ could be extracted directly from such measurements at appropriate kinematic values. Estimates of this quantity from different phenomenological quark distribution functions are shown to differ widely.