标题： 未来的费米实验室极化Drell-Yan实验 显示英文标题

标题： A Future Polarized Drell-Yan Experiment at Fermilab

摘要： 量子色动力学的一个重大挑战是试图理解核子自旋的起源。 几十年的实验测量表明，如果仅考虑夸克和胶子自旋贡献，我们当前的理解是不完整的。 在过去几年中，越来越清楚地表明，还必须包括夸克和胶子轨道角动量的贡献。 例如，海夸克轨道贡献仍然很大程度上未被探索。 能够探测海夸克轨道贡献的测量将涉及海夸克Sivers分布。 费米实验室即将进行的E1039实验将通过Drell-Yan过程，使用120 GeV非极化质子束照射极化质子靶来获取该分布。 在E1039的运动学条件下，$u$-$\bar{u}$湮灭过程主导了Drell-Yan截面（$x_{Target}$= 0.1$\sim$0.35）。 如果$\bar{u}$夸克携带零净角动量，那么测量的Drell-Yan单自旋不对称性应为零，反之亦然。 该实验是目前运行中的SeaQuest实验的延续。 显示英文摘要

摘要： One of the great challenges of QCD is trying to understand the origin of the nucleon spin. Several decades of experimental measurements have shown that our current understanding is incomplete if only the quark and gluon spin contribution is considered. Over the last few years it has become increasingly clear that the contribution from the orbital angular momentum of the quarks and gluons has to be included as well. For instance, the sea quark orbital contribution remains largely unexplored. Measurements accessing the sea quark Sivers distribution will provide a probe of the sea quark orbital contribution. The upcoming E1039 experiment at Fermilab will access this distribution via the Drell-Yan process using a 120 GeV unpolarized proton beam directed on a polarized proton target. At E1039 kinematics the $u$-$\bar{u}$ annihilation process dominates the Drell-Yan cross section ($x_{Target}$ = 0.1 $\sim$ 0.35). If the $\bar{u}$ quark carries zero net angular momentum, then the measured Drell-Yan single-spin asymmetry should be zero, and vice versa. This experiment is a continuation of the currently running SeaQuest experiment.