Continuum QCD Modeling of Hadron Properties

完全了解质子、中子和其他强相互作用的亚原子粒子的内部结构仍然是难以捉摸的。尽管粒子物理标准模型的相关部分量子色动力学(QCD)是一个成熟的理论框架，但对于像质子大小这样的大范围现象，进行计算是极其困难的。格子-QCD是一种严重依赖高性能计算资源的数值第一原理技术，只能精确计算质子和中子等粒子的某些性质。对于其他性质，研究人员依赖于身体激发良好的现象学模型。在这个更广泛的背景下，研究人员和他的学生将开发和应用改进的QCD模型来研究组成夸克和胶子在亚原子粒子中的分布，如介子、介子和质子。这些努力为杰斐逊国家加速器设施正在进行的实验工作提供了理论支持。参与这项研究的研究生将接受理论核物理方面的培训，并将有机会研究核科学前沿的研究问题，从而接受培训，为进入核科学领域急需的劳动力做好准备。在QCD中建立非微扰模型的Dyson-Schwinger方程方法保留了QCD的短距离重整化群行为，而在红外域的建模则由一种经验方法指导，该方法保留了动力学手征对称破缺，已知的动力学手征对称破缺产生了宇宙中至少98%的可见稳定物质的质量。这种方法与现有的格子-QCD的结果进行了比较，并被用来扩展和补充格子-QCD用于格子结果目前不可用的领域。这项工作将分析和解释关于亚原子粒子的夸克和胶子结构以及弹性和跃迁形状因子的实验结果。这个项目还将开发一种改进的实用方法来求解激发态介子的QCD束缚状态方程，并将探索最近提出的关于晶格-QCD的部分子分布的近似方法的局限性。

A complete understanding of the internal structure of protons, neutrons and other strongly interacting subatomic particles remains elusive. Although Quantum Chromodynamics (QCD), the relevant part of the Standard Model of particle physics, is an established theoretical framework, it is extremely difficult to perform calculations for phenomena that extend over large distances such as the size of the proton. Lattice-QCD, a numerical first-principles technique that relies heavily on high-performance computational resources, is able to calculate accurately only certain properties of particles such as protons and neutrons. For other properties, researchers rely on physically well-motived phenomenological models. In this broader context, the investigator and his students will develop and apply improved QCD models to study the distribution of constituent quarks and gluons in subatomic particles, such as pions, kaons, and protons. These efforts provide theoretical support to ongoing experimental efforts at the Jefferson National Accelerator Facility. Graduate students involved in this research will be trained in theoretical nuclear physics and will have the opportunity to work on research problems at the forefront of nuclear science, thereby receiving training that prepares them for entering the much-needed workforce in the nuclear science arena. The Dyson-Schwinger equations approach to nonperturbative model building in QCD preserves the short distance renormalization group behavior of QCD, while modeling in the infrared domain is guided by an empirical approach that preserves the dynamical chiral symmetry breaking known to generate at least 98% of the mass of visible stable matter in the universe. This approach is checked against established results of Lattice-QCD and is used to extend and complement Lattice-QCD for domains where lattice results are not presently available. This work will analyze and interpret experimental results about the quark and gluon structure of sub-atomic particles and elastic and transition form factors. This project will also develop an improved practical method for solving the QCD bound state equation for excited state mesons and will explore the limitations of a recently proposed approximate approach to parton distributions for Lattice-QCD.