Hadronic and Nuclear Structure and Dynamics

强子和核结构与动力学

• 批准号: 1613951
• 负责人: Jose Goity
• 金额: $ 24.24万
• 依托单位: Hampton University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-15 至 2021-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1613951&HistoricalAwards=false
• 关键词: Hadronic; Nuclear; Structure; Dynamics

The understanding of the strong interactions, the force that determines the structure of atomic nuclei, is one of the most challenging problems in the Standard Model of particle physics, which describes the number and properties of all the elementary particles. The fundamental theory of the strong interactions, based on the theory of quarks and gluons known as Quantum Chromodynamics (QCD), has a very complex dynamics which gives rise to the rich properties of hadrons (baryons, including protons and neutrons, and mesons and their excitations) and also to the complexity observed in nuclear interactions and structure. The challenges are therefore many and very complex. Those challenges require a variety of experimental efforts, as well as theoretical efforts. In this context, this project will further develop the connection between the fundamental theory of QCD and hadronic/nuclear physics. It is expected that tools and methods developed in that context may have a broader domain of applications. The PI is a joint appointee in the Theory Group at Jefferson Lab, providing him with the opportunity to focus on Jefferson Lab related physics. An important mission of the project is the education and training at Hampton University of graduate and undergraduate students. An additional broader impact of the project will be the PI's interaction with scientists involved in Jefferson Lab experiments.This project focuses on low and intermediate energy strong interactions in single hadron and few nucleon problems, as well as some fundamental aspects of QCD. The methods used are based in rigorous descriptions of the strong interactions known as effective theories, which are consistent with QCD, and make use of experimental as well as lattice QCD calculations results. The aim is to advance the theoretical knowledge of QCD and the develop theoretical methods. More specifically, in single hadrons, two main lines of research will be pursued: 1) Development and applications of an improved chiral effective theory in baryons, where the combination of the low energy and the 1/Nc expansions (Nc is the number of color degrees of freedom in QCD) is implemented; applications to baryon observables, and in particular to results obtained in Lattice QCD for those observables will be pursued, where in particular the quark mass dependencies accessible through Lattice QCD will be utilized for analyzing issues of convergence of the effective theory. Particular emphasis will be on the applications to baryons involving strangeness, where there are still unresolved issues with the implementation of effective theories due to the relatively large mass of the strange quark. In particular, these studies have impact in for improving the accuracy of the extraction of weak interaction parameters from hyperon decays. 2) Study of excited baryons in the framework of the 1/Nc expansion, which has as main aim the use of that fundamental expansion of QCD to organize the description of baryon resonances; this work has an impact in the analysis of current experimental results on baryon resonances from various facilities, in particular Jefferson Lab, and it can also be applied to the current Lattice QCD calculations of the excited baryon spectrum. In few body physics, the research is focused on applying the combined chiral effective theory and 1/Nc expansion to study the nucleon-nucleon interaction. Among the fundamental aspects of QCD, the project will focus on pure glue-dynamics, studying its fundamental non-perturbative quantities, namely gluon condensate and topological susceptibility using methods of holographic QCD.

对强相互作用的理解，决定原子核结构的力，是粒子物理学标准模型中最具挑战性的问题之一，它描述了所有基本粒子的数量和性质。强相互作用的基本理论，基于夸克和胶子的理论，称为量子色动力学（QCD），具有非常复杂的动力学，产生了强子（重子，包括质子和中子，以及介子及其激发）的丰富性质，也产生了在核相互作用和结构中观察到的复杂性。因此，挑战很多而且非常复杂。这些挑战需要各种实验努力以及理论努力。在此背景下，该项目将进一步发展QCD基础理论与强子/核物理之间的联系。预计在这方面开发的工具和方法可能有更广泛的应用领域。PI是杰斐逊实验室理论小组的联合任命者，为他提供了专注于杰斐逊实验室相关物理的机会。该项目的一个重要使命是在汉普顿大学对研究生和本科生进行教育和培训。该项目的另一个更广泛的影响将是PI的 与参与Jefferson实验室实验的科学家的互动。该项目侧重于单个强子和少数核子中的低能量和中能量强相互作用问题，以及QCD的一些基本方面。所使用的方法是基于强相互作用的严格描述称为有效理论，这是一致的QCD，并利用实验以及晶格QCD计算结果。其目的是促进QCD的理论认识和理论方法的发展。具体来说，在单强子中，我们将沿着两条主线进行研究：1）改进的重子手征有效理论的发展和应用，其中结合低能和1/Nc展开（Nc是QCD中颜色自由度的数目）;应用到重子观测量，特别是在格点QCD中得到的结果，这些观测量将被追求，特别是夸克的质量依赖性可通过格点QCD将用于分析问题的有效理论的收敛。特别强调的是涉及奇异性的重子的应用，由于奇异夸克的质量相对较大，在有效理论的实施方面仍然存在未解决的问题。特别是，这些研究对提高从超子衰变中提取弱相互作用参数的准确性具有重要意义。2)在1/Nc展开的框架下研究受激重子，其主要目的是使用QCD的基本展开来组织重子共振的描述;这项工作对分析当前来自各种设施的重子共振实验结果产生了影响，特别是Jefferson实验室，它也可以应用于当前的受激重子谱的晶格QCD计算。在少体物理中，研究的重点是将手征有效理论和1/Nc展开相结合来研究核子-核子相互作用。 在QCD的基本方面中，该项目将侧重于纯胶动力学，使用全息QCD方法研究其基本非微扰量，即胶子凝聚和拓扑磁化率。