Drell-Yan Studies at Fermilab

核子、质子和中子都是由更基本的夸克组成的，这一点现在已是公认的事实。该奖项支持的主要物理学计划旨在研究核子的夸克结构以及由这些核子组成的原子核。这项研究将在芝加哥附近的费米实验室进行，作为一项名为SeaQuest的合作的一部分。这项合作的重点是生产称为μ子的粒子对，它们像电子但质量更大，用作核子中反夸克分布的探针（以及这些分布是否在核中被修改）。这些信息将为质子的理论模型提供直接输入，并阐明质子自旋的起源。一个相关的研究，使用极化质子束，将提供新的信息的对称性的夸克分布的基础上的预测，从量子色动力学的基本理论。此外，密歇根大学将领导SeaQuest实验中低温氢靶的操作，并参与下一代实验的极化氢靶的开发。本科生和研究生的教育和培训，以及针对公众的推广，是这个研究计划的一个重要方面。芝加哥附近费米实验室的SeaQuest实验将更好地了解轻反夸克如何分布在核子和原子核中，产生核子海的物理机制，以及轨道角动量如何有助于核子自旋。一个较小的，但非常重要的努力将花在发展极化Drell-Yan程序在费米实验室，是补充在布鲁克海文国家实验室和杰斐逊实验室的自旋物理程序。该计划建立在该小组所获得的专业知识的基础上，是该小组过去几年工作的自然延伸。它使他们能够在费米实验室的Drell-Yan实验中发挥重要作用，并在未来引领费米实验室的极化Drell-Yan计划。

It is now a well-established fact that nucleons, protons and neutrons, are made up of more elementary particles called quarks. The main physics program supported by this award is directed at the study of the quark structure of nucleons and the nuclei that are made up of these nucleons. Research will be carried out at the Fermilab Laboratory near Chicago as part of a collaboration called SeaQuest. This collaboration is focused on the production of pairs of particles called muons, which are like electrons but more massive, used as a probe of the anti-quark distributions in the nucleon (and whether these distributions are modified in nuclei). This information will provide direct input to theoretical models of the proton, and shed light on the origin of the proton's spin. A related study, using a polarized proton beam, will provide new information on symmetries of the quark distributions based on predictions from the fundamental theory of Quantum Chromodynamics. In addition, the Michigan group will lead the operation of the low-temperature hydrogen targets at the SeaQuest experiment, and participate in the development of a polarized hydrogen target for a next-generation experiment. Education and training of both undergraduate and graduate students, as well as outreach aimed at the general public, is an important aspect of this research program. The SeaQuest experiment at the Fermilab Laboratory near Chicago will provide a better understanding how light anti-quarks are distributed in nucleons and nuclei, on the physical mechanism that generates the sea of the nucleon, and how orbital angular momentum might contribute to the nucleon spin. A smaller, but very important effort will be spent on developing a polarized Drell-Yan program at Fermilab that is complementary to the spin physics programs at Brookhaven National Lab and Jefferson Lab. This program builds on the expertise the group has gained, and is a natural extension of the group's work over the past years. It allows them to play a major role in the Drell-Yan experiment at Fermilab now, and to lead the way towards a polarized Drell-Yan program at Fermilab in the future.