Final SeaQuest results on the flavor asymmetry of the proton light-quark sea with proton-induced Drell-Yan process

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 ${\sigma }_{pd}\mathrm{/}2{\sigma }_{pp}$ Drell-Yan cross section ratio covering the kinematic region of $0.13<x<0.45$. The $x$-dependencies of $\bar{d}\left(x\right)\mathrm{/}\bar{u}\left(x\right)$ 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 $\bar{d}\left(x\right)\mathrm{/}\bar{u}\left(x\right)$ and $\bar{d}\left(x\right)-\bar{u}\left(x\right)$ are compared to various parton distribution functions and theoretical calculations.