Studies of the Structure of Light Mesons and Nucleons through Exclusive Reactions

介子和介子是最轻的亚原子粒子，在自然界中起着独特的作用；我们对它们的理解对于解释物质的基本结构至关重要。这项研究集中在对介子和介子性质的精确测量上，这些性质有可能揭示核子、质子和中子的三维结构，它们以及它们之间的相互作用产生了几乎可见宇宙的质量。因此，这项工作探索了我们所能看到的那部分宇宙的基本结构。这个项目是在托马斯·杰斐逊国家加速器实验室进行的一系列实验的一部分。早期职业科学家、研究生和本科生在这个项目中发挥着不可或缺的作用，这为他们提供了进一步发展他们的培训和教育的机会。这些包括在辐射和亚原子粒子探测、快速信号处理电子和分析科学数据的现代仪器的设计、组装和测试方面获得经验。此外，学习在大型国际科学界工作将为早期职业科学家和学生在学术机构、国家实验室和工业的现代工作环境做好准备。该计划的重点是精确测量介子和介子的形状因子和结构功能，并验证我们对3D强子成像和潜在的未来风味分解的硬独占和半包容反应的理解。形状因子是理解横向空间结构的最基本的量。海夸克和胶子的介子、介子和核子的结构函数预计会有所不同，并提供质量起源的基本信息。三维强子成像允许利用因式分解定理从实验中提取夸克纵向动量和横向位置之间的相关性。为了验证介子分解定理和潜在的未来风味分解，必须测量纵向和横向（L/T）分离截面。该项目通过在12gev杰斐逊实验室进行精确的介子和介子L/T分离截面测量，以及在潜在的未来电子-离子对撞机上对迄今为止大部分未知的介子和介子结构功能的测量发展，在这项工作中发挥了核心作用。

Pions and kaons are the lightest subatomic particles and play a unique role in nature; our understanding of them is essential for explaining the fundamental structure of matter. This research is centered on precision measurements of pion and kaon properties that have the potential to reveal the three-dimensional structure of the nucleons, the protons and neutrons that, together with their interactions, generate nearly of the mass of the visible universe. As such, this work probes the fundamental structure of that part of the universe that we can see. This project is part of a series of experiments taking place at the Thomas Jefferson National Accelerator Laboratory. Early career scientists, graduate students, and undergraduate students play an integral part in this project, which provides them with opportunities to further develop their training and education. These include gaining experience in the design, assembly, and testing of modern instrumentation for the detection of radiation and subatomic particles and fast signal processing electronics, and in analyzing scientific data. Furthermore, learning to work in a large international scientific community will prepare early career scientists and students for the modern work environment at academic institutions, national laboratories, and industry. This program is focused on precision measurements of pion and kaon form factors and structure functions, and validation of our understanding of hard exclusive and semi-inclusive reactions towards 3D hadron imaging and potential future flavor decomposition. Form factors are the most basic quantity towards understanding transverse spatial structure. The structure functions are expected to be different for pions, kaons, and nucleons regarding sea quarks and gluons and provide basic information about the origin of mass. 3D hadron imaging allows for the extraction of correlations between quark longitudinal momentum and transverse position from the experiment using factorization theorems. To validate the meson factorization theorems and potential future flavor decomposition, one has to measure the longitudinal and transverse (L/T) separated cross sections. This project plays a central role in this effort through precision pion, and kaon L/T separated cross section measurements at the 12 GeV Jefferson Lab and development of measurements of the, to date, mostly unknown pion and kaon structure functions at a potential future Electron-Ion Collider.