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

TL;DR

The SeaQuest experiment measured the proton's light-quark sea asymmetry using proton-induced Drell-Yan processes, providing high-precision data that confirms an excess of ar; over ar; across a broad x range.

Contribution

This work presents the final results of the SeaQuest experiment, offering the most precise measurements of the ar;/ar; ratio and difference, advancing understanding of proton structure.

Findings

ar; exceeds ar; across 0.13 < x < 0.45.

Improved statistical accuracy over previous measurements.

Results align with certain theoretical models and parton distribution functions.

Abstract

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.