On the shape of the d¯−u¯ asymmetry

Abstract Using data from a recent reanalysis of neutron structure functions extracted from inclusive proton and deuteron deep-inelastic scattering (DIS), we re-examine the constraints on the shape of the d ¯ − u ¯ asymmetry in the proton at large parton momentum fractions x. A global analysis of the proton–neutron structure function difference from BCDMS, NMC, SLAC and Jefferson Lab DIS measurements, and of Fermilab Drell-Yan lepton-pair production cross sections, suggests that existing data can be well described with d ¯ > u ¯ for all values of x currently accessible. We compare the shape of the fitted d ¯ − u ¯ distributions with expectations from nonperturbative models based on chiral symmetry breaking, which can be tested by upcoming Drell-Yan data from the SeaQuest experiment at larger values of x.