Hadronic Structure and Dynamics

该项目将对物理强子进行研究，强子是夸克和胶子的可观测复合物。这些研究与两种强子的现象学，即介子和重子，以及对强相互作用基本理论的复杂非微扰域的进一步理解有关，即量子色动力学（QCD）。其中一项研究将通过称为QCD的1/N展开的理论框架来解决激发态重子的现象学问题，其中N是颜色自由度的数量，在自然界中等于3。本研究的主要目的是用符合量子光盘结构的框架描述激发态重子的质量、强衰变和光产生过程。该计划与目前杰斐逊实验室的激发态重子实验计划相关。对1/N展开的一些基本方面的理论研究也将进行，特别是关注QCD中手性对称性的自发破缺现象。另一项研究将用有效的理论来描述低能和中能的QCD。特别是，该项目将考虑扩展QCD的低能量有效理论（即手性微扰理论）的有效性范围的问题。计划是制定一个有效的理论，其中低洼介子共振包括作为主动自由度。这种新的有效理论将有助于更准确地描述发生在普通手性微扰理论适用范围之外的过程。总之，该项目的目标是通过与QCD一致的方法来研究强相互作用的物理学，主要目的是通过这种方式获得具有普遍有效性的严格结果。该项目还有一个重要的教育组成部分，包括培养一名博士生，与博士后合作，以及为研究生课程开发基于计算机的教材。

This project will carry out studies in the physics hadrons, which are the observable composites of quarks and gluons. These studies are relevant to the phenomenology of two kinds of hadrons, namely mesons and baryons, as well as to the further understanding of the complex non-perturbative domain of the fundamental theory of strong interactions known as Quantum Chromodynamics (QCD). One of these studies will address the phenomenology of excited baryons by means of a theoretical framework known as the 1/N expansion of QCD, where N is the number of color degrees of freedom, equal to three in nature. The main goal of this study is to describe masses, strong decays and processes of photo-production of excited baryons with a framework that is consistent with the strictures of QCD. This plan is of relevance to the current experimental program on excited baryons at Jefferson Lab. Theoretical studies of some fundamental aspects of the 1/N expansion will also be carried out, especially with focus on the phenomenon of spontaneous breaking of chiral symmetry in QCD. Another study will address the problem of describing QCD at low and intermediate energies with effective theories. In particular, the project will consider the problem of extending the range of validity of the low energy effective theory of QCD known as Chiral Perturbation Theory. The plan is to formulate an effective theory where low-lying meson resonances are included as active degrees of freedom. This new effective theory will help describe with better accuracy processes that take place outside the range of applicability of ordinary Chiral Perturbation Theory. In summary, the objective of the project is in the study of the physics of the strong interactions by means of methods that are consistent with QCD, and the main aim is to arrive in this way at rigorous results that have general validity. The project has also an important education component that includes the training of a PhD student, collaboration with postdoctoral associates, and the development of computer based teaching materials for graduate courses.