Bayesian Monte Carlo extraction of the sea asymmetry with SeaQuest and STAR data

We perform a global QCD analysis of unpolarized parton distributions within a Bayesian Monte Carlo framework, including the new $W$-lepton production data from the STAR Collaboration at RHIC and Drell-Yan dimuon data from the SeaQuest experiment at Fermilab. We assess the impact of these two new measurements on the light antiquark sea in the proton and the $\overline{d}\ensuremath{-}\overline{u}$ asymmetry in particular. The SeaQuest data are found to significantly reduce the uncertainty on the $\overline{d}/\overline{u}$ ratio at large parton momentum fractions $x$, strongly favoring an enhanced $\overline{d}$ sea up to $x\ensuremath{\approx}0.4$, in general agreement with nonperturbative calculations based on chiral symmetry breaking in QCD.