质子结构与质子自旋组成是什么?  

What is the structure and spin decomposition of the proton?

作　　者：宋玉坤[1] 周剑[2] 梁作堂 Yukun Song;Jian Zhou;Zuotang Liang(School of Physics and Technology,University of Jinan,Jinan 250022,CHINA;Key Laboratory of Particle Physics and Particle Irradiation（MOE）Qingdao 266237,China)

机构地区：[1]济南大学物理科学与技术学院,济南250022 [2]山东大学前沿交叉科学青岛研究院粒子物理与粒子辐照教育部重点实验室,青岛266237

出　　处：《科学通报》2018年第24期2546-2556,共11页Chinese Science Bulletin

摘　　要：质子结构是人们对物质深层次结构认识的最前沿,高能反应实验特别是电子质子深度非弹性散射实验的开展,推动了理论研究的不断深入,发展出量子色动力学基础上的部分子模型,成为描述质子结构的标准动力学图像,更新了人们对物质结构认识的观念,也为检验量子色动力学、研究其性质与应用方法提供了一个核心前沿基地,发展出因子化定理与共线展开等重要方法.而近年来实验对质子自旋结构、质子电磁半径的测量相继引发的"质子自旋之谜"与"质子半径之谜"等,更加激发了粒子物理与核物理学界的研究兴趣,对质子结构的研究也从简单的一维纵向运动深入到包括横动量和自旋依赖的三维情形,从单纯的数密度分布扩展到各类的自旋与动量关联函数,包括描述量子干涉效应在内的阶压低的高扭度分布函数,研究内容与研究方法不断地更新.近期新的实验基地,如美国电子离子对撞机等的建设更将推动该方向研究迎来快速发展的高峰期,我国规划中的相应的大科学装置也有望在该领域的研究中发挥重要作用.The structure of the proton is the forefront of studies on the deep structure of matter. With developments of high energy experiments in particular deeply inelastic lepton nucleon scattering （DIS）, a dynamical picture of the structure of the proton has been developed, i.e., the quantum chromodynamics （QCD） based parton model. According to this picture, a proton moving close to the speed of light can be viewed as a bunch of free partons, and the collision between two high energy protons can be viewed as the collision between partons. Partons in the proton are described by parton distribution functions （PDFs）. This picture is very successful in describing data from different experiments. It has been widely ac- cepted in high energy physics community and is now taken as the standard picture for the dynamical structure of hadrons. The picture has changed the concepts of structures of matter in the sense that the number of partons in a proton depends on the space and time resolution of the probe. The studies of the proton structure provide not only the necessary initial condition of high energy collision but also the most active and fruitful frontier for studying properties of QCD where new QCD application techniques have been developed such as the collinear expansion and factorization theorem. With developments of experimental techniques, the studies have been extended to include spin degree of freedom and to use different probes such as electrons and muons. These studies have lead to many new discoveries, initiated the well known ＂proton spin crisis＂ and the ＂proton radius puzzle＂, and attracted much more attention in the field of particle and nuclear physics. The experimental data from polarized DIS has revealed that quark spin contributes to only a small frac- tion of the proton spin and initiated the question where the proton spin comes from. The electromagnetic radius of the proton measured from the electron-proton interaction does not coincide with that measured from the muon-proton inter-

关 键 词：质子结构 质子半径之谜 质子自旋之谜 部分子模型 量子色动力学 因子化定理 共线展开 

分 类 号：O572.2[理学—粒子物理与原子核物理]