The Fermilab E906/SeaQuest collaboration performed measurements of the Drell-Yan process using 120 GeV proton beams bombarding liquid hydrogen and liquid deuterium targets. A combined analysis of all collected data was performed to obtain the final results for the $\sigma_{ pd}/2\sigma_{ pp}$ Drell-Yan cross section ratio covering the kinematic region of $0.13 < x < 0.45$. The $x$-dependencies of $\bar{ d}\left(x\right) / \bar{ u}\left(x\right)$ and $\bar{ d}\left(x\right) - \bar{ u}\left(x\right)$ are extracted from these cross section ratios. It is found that $\bar{ d}\left(x\right)$ is greater than $\bar{ u}\left(x\right)$ over the entire measured $x$ range, with improved statistical accuracy compared to previous measurements. The new results on $\bar{ d}\left(x\right) / \bar{ u}\left(x\right)$ and $\bar{ d}\left(x\right) - \bar{ u}\left(x\right)$ are compared to various parton distribution functions and theoretical calculations.
Categories: hep-ex nucl-ex