Chiral Dynamics in the Nucleon Quark Sea

现代核物理学的一个重要探索涉及到从夸克、反夸克和胶子的角度对核子（质子和中子）结构的理论理解，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，研究者和他的学生将推动理论的发展，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，本项目的好处还包括培养研究生。该项目还将为理论核子结构研究前沿的本科生提供研究机会。本计画将探讨核子结构的横向动量相关部分分布函数（TMDs）。基于QCD分解形式，tmd是研究高能反应的一个有用工具。与我们所熟知的共线部分分布函数（描述没有最终状态横向动量的过程）相比，tmd提供了关于动力学的详细信息。它们提供了探索偏振光束和目标时的部分子轨道运动和自旋轨道相关方面的途径。该项目的目标是在非微扰框架中推进对tmd性质的当前理解。该项目的具体目标是：(1)在低初始尺度下确定tmd的非微扰特性；(2)识别以海夸克效应为重点的手性对称性破缺的模型无关特征；(3)探索现象学应用并提出实验预测。本项目使用的工具包括微扰演化方程、动力学模型和有效手性理论。

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.