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

可见的宇宙是由核子（质子和中子）和电子组成的。核子本身是部分子、夸克和胶子的相互作用动力学系统--强相互作用理论的自由度，量子染色体动力学（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。该项目的主要目标是推进QCD中核子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。该项目扩大了电子离子对撞机（EIC）未来计划的影响，这是一个强大的新设施，将在美国建造，以及杰斐逊实验室和布鲁克海文国家实验室的现有计划，通过进行现象学和理论研究，提供分析，解释目前的数据，并预测未来的测量。该项目通过提供和开发现代统计学和核物理学课程，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研讨会，为教育具有世界一流技能的多元化全球参与劳动力做出贡献。该项目的主要目标是推进核子三维动量和自旋结构的理论和唯象研究，并绘制其内部景观编码的横向动量依赖部分子分布和碎裂函数（TMD）。TMD在理解部分子和核子的内禀运动和自旋之间的相关性方面至关重要，这些相关性产生了在各种散射过程中测量到的自旋不对称性。该项目旨在通过对来自世界设施的实验数据进行全球QCD分析，以高微扰精度提取核子的非极化三维结构，这些设施包括爱马仕（DESY），COMPASS（CERN），杰斐逊实验室，贝儿（KEK），BaBar（SLAC），BESIII（北京），RHIC（BNL）和LHC（CERN）。该研究涉及对数据的全球QCD分析，统一了共线和TMD物理。该项目还侧重于使用所有可用的世界数据研究核子的自旋结构，并提取极化TMD，如Sivers函数，transversity，柯林斯碎裂函数等。此外，该项目将结合联合收割机TMD相关测量和相对论重离子对撞机（RHIC，BNL）的极化质子-质子散射数据与twist-3因子分解相关。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值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.