RUI: Three Dimensional Structure of the Nucleon in QCD

探索核子（原子核中的质子或中子）的内部结构是现代核物理学的主要目标之一。我们对核子的理解是一个由更基本的粒子、夸克和胶子（统称为部分子）组成的相互作用系统，这是基于强相互作用理论，即量子染色体动力学（QCD）。部分子在核子内部既受限制又运动。结合部分子运动对核子结构的探索将使我们获得有关核子三维结构的新信息。 了解组成部分如何联合收割机结合在一起，对于理解我们所观察到的核子的性质至关重要。 PI将致力于改进核子3D结构的现象学描述，并将开发一个基于PSU Berks的网络接口服务器，以使研究人员和公众可以获得结果。本科生将通过该项目得到培训和支持。该项目的科学目标是从现有的实验数据中精确提取描述3D核子结构的横向动量相关分布和碎裂函数（TMD）。TMD与部分子运动和部分子自旋和/或核子自旋的相关性密切相关，并在散射过程中产生自旋不对称性。该项目旨在统一现有的三维核子结构描述的形式，并最终探索各种过程中自旋不对称性的起源。研究中将使用来自过去和现有设施的数据，如爱马仕（DESY）、COMPASS（CERN）、杰斐逊实验室、贝儿（KEK）、BaBar（SLAC）、BESIII（北京）、RHIC（BNL）、LHC（CERN）。该项目的结果将有助于规划杰斐逊实验室12的未来实验，以及未来的电子离子对撞机。该项目还将导致提取核子的基本电荷，特别是核子的张量电荷，这对超越标准模型（BSM）物理学的搜索非常重要，并补充了其在格点QCD中的计算工作。

Exploration of the internal structure of the nucleon, the proton or neutron in the nucleus, is one of the main goals of modern nuclear physics. Our understanding of the nucleon as an interacting system of yet more fundamental particles, quarks and gluons, collectively called partons, is based on the theory of strong interactions, Quantum Chromo Dynamics (QCD). Partons are both confined and moving inside of the nucleon. The exploration of the nucleon structure that incorporates the motion of partons will allow us to gain new information on the three dimensional (3D) structure of the nucleon. Knowing how the constituent parts combine together is essential to understanding the properties of the nucleon that we observe. The PI will work towards an improved phenomenological description of the 3D structure of the nucleon and will develop a web interface server based at PSU Berks to make the results available to researchers and the general public. Undergraduate students will be trained and supported by this project. The scientific goals of the project are to extract precisely the Transverse Momentum Dependent distribution and fragmentation functions (TMDs) that describe the 3D nucleon structure, from the existing experimental data. TMDs are intimately related to the correlations of parton motion and the spin of the parton and /or the spin of the nucleon and generate Spin Asymmetries in scattering processes. The project is intended to unify existing formalisms of the description of the 3D nucleon structure, and ultimately explore the origin of the Spin Asymmetries in various processes. The data from past and existing facilities, such as HERMES (DESY), COMPASS (CERN), and Jefferson Lab, BELLE (KEK), BaBar (SLAC), BESIII (Beijing), RHIC (BNL), LHC (CERN), will be used in the studies. The results of the project will help with planning future experiments at Jefferson Lab 12, and a future Electron Ion Collider. The project will also lead to the extraction of fundamental charges of the nucleon, in particular, the nucleon's tensor charge, which is important for searches of Beyond Standard Model (BSM) physics and complements efforts of its calculation in Lattice QCD.