Hadronic and Nuclear Structure and Dynamics

该项目的目标是通过应用和发展广泛基于有效理论概念的方法来推进对强子和轻核的理论认识。这些有效的理论允许对强子和核系统进行描述，并与强相互作用的基本理论量子色动力学（QCD）保持严格的联系。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。这个计划与目前杰斐逊实验室和其他地方的激发态重子实验计划有关。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，该项目将考虑通过在有效理论中包含激发态介子，将QCD的低能量有效理论（即手性微扰理论）的有效性范围扩展到中间能量域的问题。有效理论在核物理中的应用将集中在核电流矩阵元素的低能展开的研究上，特别是电磁电流的低能展开，它可能有大量的现象学应用。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和与博士后合作伙伴的合作。

The goals of this project are to advance the theoretical understanding of hadrons and light nuclei through the application and development of methods broadly based on the concept of effective theories. These effective theories allow for a description of hadronic and nuclear systems preserving a rigorous connection with the fundamental theory of the strong interactions, 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. This plan is of relevance to the current experimental programs on excited baryons at Jefferson Lab and elsewhere. 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 the 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 to the intermediate energy domain through the inclusion of excited meson states in the effective theory. The application of effective theories to nuclear physics will focus on the study of the low energy expansion of nuclear current matrix elements, in particular electromagnetic currents, for which a large number of phenomenological applications are possible. The project has also an important education component, which includes the training of a PhD student and collaborations with postdoctoral associates.