Chiral Dynamics in the Nucleon Quark Sea

现代核物理中的一个重要探索涉及到从理论上理解夸克、反夸克和胶子中的核子结构、量子色动力学(QCD)的自由度、强相互作用的基本理论。在这个项目中，研究人员和他的学生将推动必要的理论发展，以理解托马斯·杰斐逊国家实验室、布鲁克海文国家实验室和世界各地其他设施的实验。除了为现有和未来的实验项目提供理论支持外，该项目的好处还包括为研究生提供培训。该项目还将为本科生提供理论核子结构研究前沿的研究机会。该项目将根据横向动量相关的部分子分布函数(TMD)来探索核子结构。基于QCD因式分解理论，TMD是研究高能反应的有用工具。与我们熟知的描述末态横向动量不被分辨的过程的共线部分子分布函数相比，TMD提供了关于动力学的详细信息。当探索极化光束和目标时，它们提供了部分子轨道运动和自旋-轨道关联的方面的途径。该项目的目标是在非微扰框架内促进对TMD性质的当前理解。该项目的具体目标是：(1)确定TMD在低初始尺度下的非微扰性质，(2)识别与模型无关的手征对称性破缺特征，重点关注海夸克效应，(3)探索唯象应用并为实验提供预测。这个项目中使用的工具包括微扰演化方程、动力学模型和有效的手征理论。

An important quest in modern nuclear physics concerns the theoretical understanding of the structure of nucleons (protons and neutrons) in terms of quarks, antiquarks and gluons, the degrees of freedom of quantum chromodynamics (QCD), the fundamental theory of strong interactions. In this project, the investigator and his students will advance the development of theory necessary to understand experiments at the Thomas Jefferson National Laboratory, Brookhaven National Laboratory, and other facilities world-wide. In addition to providing theoretical support for existing and future experimental programs, the benefits of this project include training for graduate students. The project will also offer research opportunities for undergraduate students at the frontiers of theoretical nucleon structure research.This project will explore nucleon structure in terms of transverse momentum dependent parton distribution functions (TMDs). Based on a QCD factorization formalism, TMDs are a useful tool in the study of high-energy reactions. As compared to the familiar and better known collinear parton distribution functions which describe processes when no final-state transverse momenta are resolved, TMDs offer detailed information about dynamics. They provide access to parton orbital motion and aspects of spin-orbit correlations when polarized beams and targets are explored. The goal of this project is to advance the current understanding of the properties of TMDs in a non-perturbative framework. The specific objectives of the project are: (1) determine the non-perturbative properties of TMDs at a low initial scale, (2)identify model-independent signatures of chiral symmetry breaking with focus on sea quark effects, (3) explore phenomenological applications and present predictions for experiments. The tools employed in this project include the use of perturbative evolution equations, dynamical models, and effective chiral theories.