RUI: The 3D Momentum and Spin Structure of the Nucleon in QCD

可见宇宙由核子(质子和中子)和电子组成。核子本身是部子、夸克和胶子相互作用的动力学系统--强相互作用理论的自由度，即量子色动力学(QCD)。揭示核子的QCD夸克和胶子结构是现代核物理的一个重要研究领域。这个项目的主要目标是推进QCD中核子的三维动量和自旋结构的理论和唯象研究。通过这样做，该项目旨在发现核子的内部景观。该项目通过进行现象学和理论研究，提供对当前数据的分析、解释和对未来测量的预测，扩大了即将在美国建造的强大的新设施电子离子对撞机(EIC)的未来计划以及杰斐逊实验室和布鲁克海文国家实验室现有计划的影响。该项目通过提供和开发有关现代统计学和核物理的课程、为研究生组织和教授暑期学校以及举办关于核子三维结构的年度讲习班，促进培养一支具有世界级技能的多样化的全球工作人员队伍。这个项目的主要目的是推进核子三维动量和自旋结构的理论和唯象研究，并绘制出以横向动量相关的部分子分布和碎裂函数(TMD)编码的核子内部景观。TMD对于理解部子和核子的本征运动和自旋之间的关联至关重要，核子产生了在各种散射过程中测量到的自旋不对称。该项目的目的是通过对来自世界设施的实验数据进行全球QCD分析，以高精度地提取核子非极化的三维结构。这些设施包括爱马仕(DESY)、COMPASS(CERN)、杰斐逊实验室(Jefferson Lab)、Belle(KEK)、Babar(SLAC)、BESIII(北京)、RHIC(BNL)和LHC(CERN)。这项研究涉及对数据的全球QCD分析，统一了共线和TMD物理学。该项目还专注于利用所有可用的世界数据来研究核子的自旋结构，并提取极化的TMD，如Sivers函数、横度、Collins碎裂函数等。此外，该项目将结合与TMD相关的测量和相对论重离子对撞机(RHIC，BNL)与TWIST-3因式分解相关的极化质子-质子散射数据。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The visible universe is made up of nucleons (protons and neutrons) and electrons. Nucleons themselves are interacting dynamical systems of partons, quarks, and gluons—the degrees of freedom of the theory of strong interactions, Quantum Chromo Dynamics (QCD). Unfolding the QCD quark and gluon structure of nucleons is a crucial area of study in modern nuclear physics. The main objective of this project is to advance theoretical and phenomenological studies of the three-dimensional (3D) momentum and spin structure of the nucleon in QCD. By doing this, the project aims to discover the internal landscape of the nucleon. This project expands the impact of the future program at the Electron-Ion Collider (EIC), a powerful new facility to be built in the United States, as well as of the existing programs at Jefferson Lab and Brookhaven National Laboratory, by performing phenomenological and theoretical studies, providing analysis, explanation of present data, and predictions for future measurements. The project contributes to the education of a diverse, globally engaged workforce with world-class skills by providing and developing courses on modern statistics and nuclear physics, organizing and teaching summer schools for graduate students, and running annual workshops on the 3D structure of the nucleon. The main objective of this project is to advance the theoretical and phenomenological studies of the 3D momentum and spin structure of the nucleon, and to map its internal landscape encoded in the Transverse Momentum Dependent parton distribution and fragmentation functions (TMDs). TMDs are crucial in understanding the correlations between the intrinsic motion and spin of partons and the nucleon, which generate Spin Asymmetries measured in various scattering processes. The project aims to extract the unpolarized 3D structure of the nucleon with high perturbative precision by performing a global QCD analysis of data from experiments from world facilities, including HERMES (DESY), COMPASS (CERN), Jefferson Lab, BELLE (KEK), BaBar (SLAC), BESIII (Beijing), RHIC (BNL), and LHC (CERN). The study involves a global QCD analysis of the data, unifying collinear and TMD physics. The project also focuses on studying the spin structure of the nucleon using all available world data, and extracting polarized TMDs such as Sivers functions, transversity, Collins Fragmentation Functions, and others. In addition, the project will combine TMD-related measurements and the polarized proton-proton scattering data from the Relativistic Heavy Ion Collider (RHIC, BNL) related to twist-3 factorization.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.