Probing the flavor dependence of proton's light-quark sea in the SeaQuest experiment

Abstract

Surprisingly large flavor asymmetry of the light-quark sea in the proton was reported in deep-inelastic scattering and Drell-Yan experiments. The Bjorken-$x$ dependence of the $\bar{d}/\bar{u}$ ratio extracted from the Fermilab E866 experiment also revealed an intriguing drop at the highest values of $x$. The Fermilab E906/SeaQuest experiment was designed to measure $\bar{d}/\bar{u}$ with improved accuracy at high Bjorken-$x$. By detecting high-mass dimuon events produced in the interaction of 120 GeV proton beam with liquid hydrogen (LH$_2$) and deuterium (LD$_2$) targets, the SeaQuest experiment probes the $\bar{d}/\bar{u}$ ratio up to $x \approx 0.45$. Data collection has been completed and we report the status of data analysis for SeaQuest. Two different methods for extracting the LD$_2$/LH$_2$ Drell-Yan cross section ratios for $0.1\leq x\leq 0.45$ are discussed. These ratios are compared with calculations using various PDFs.