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

RUI：QCD 中核子的 3D 动量和自旋结构

• 批准号: 2310031
• 负责人: Alexey Prokudin
• 金额: $ 21.3万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2310031&HistoricalAwards=false
• 关键词: RUI; 3D; Momentum; Spin; Structure

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.

可见宇宙由核子（质子和中子）和电子组成。核子本身是由部分子、夸克和胶子组成的相互作用的动力系统——强相互作用理论、量子色动力学（QCD）的自由度。揭示核子的 QCD 夸克和胶子结构是现代核物理学的一个重要研究领域。该项目的主要目标是推进 QCD 中核子的三维 (3D) 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和解释以及对未来测量的预测，扩大了电子离子对撞机（EIC）未来计划的影响，电子离子对撞机是一个将在美国建造的强大新设施，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现代统计和核物理课程、为研究生组织和教授暑期学校以及举办有关核子 3D 结构的年度研讨会，为培养具有世界一流技能的多元化、全球参与的劳动力队伍做出贡献。该项目的主要目标是推进核子 3D 动量和自旋结构的理论和现象学研究，并绘制以横向动量相关部分子分布和碎片函数 (TMD) 编码的内部景观图。 TMD 对于理解部分子和核子的固有运动和自旋之间的相关性至关重要，这些相关性会产生在各种散射过程中测量的自旋不对称性。该项目旨在通过对来自世界各地设施的实验数据进行全局 QCD 分析，以高微扰精度提取核子的非偏振 3D 结构，这些设施包括 HERMES (DESY)、COMPASS (CERN)、Jefferson Lab、BELLE (KEK)、BaBar (SLAC)、BESIII（北京）、RHIC (BNL) 和 LHC (CERN)。该研究涉及对数据进行全局 QCD 分析，统一共线和 TMD 物理。该项目还重点利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，例如 Sivers 函数、横断函数、柯林斯碎片函数等。此外，该项目将结合TMD相关测量和来自相对论重离子对撞机（RHIC，BNL）与twist-3分解相关的偏振质子-质子散射数据。该奖项反映了NSF的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。