New Tools to Study Strong Interaction Physics

公认的将原子核聚集在一起的强核力理论，称为QCD(量子色动力学)，已经知道35年了，但它的使用非常困难，在它最突出的区域也鲜为人知；例如，我们知道质子和中子(统称为核子)是由更小的夸克和胶子组成的，但它们到底是如何组装成核子的，充其量仍然不清楚。在这笔赠款中，别里茨基和勒贝德将使用各种高性能的数学工具，通常是借用自弦理论的工具，以在这一复杂的格局中取得进展。别里茨基是广义部分子分布理论方面的专家，广义部分子分布是核子可能最精确定义的观测数据，而勒贝德则是大型NC QCD的专家，在这种情况下，通过增加比自然界中发生的更多的自由度，求解QCD变得简单得出奇。此外，别里茨基还精通于一种名为可积性的强大技术，在这种技术中，QCD和类似的理论可以在数学上与铁磁体和其他自旋链等系统的物理相关。与此同时，勒贝德正在研究“全息QCD”，这是基于弦理论的一个想法，即QCD和相关的强相互作用理论可以与弯曲空间上的弱相互作用引力有关。别里茨基和列别德将在这些项目领域分别指导一名博士生。

The accepted theory of the strong nuclear force that holds atomic nuclei together, called QCD (Quantum Chromodynamics) has been known for 35 years, but is extraordinarily difficult to use and is poorly understood in precisely the regions where it is most prominent; for example, we know that protons and neutrons (collectively, "nucleons") are made of smaller constituents named quarks and gluons, but exactly how they are assembled into nucleons remains murky at best. In this grant, Belitsky and Lebed will use a variety of high-powered mathematical tools, often ones borrowed from string theory, to make headway in this complicated landscape. Belitsky is an expert in the theory of generalized parton distributions, which are the most precisely defined observables possible for nucleons, while Lebed is an expert on large Nc QCD, in which solving QCD becomes paradoxically simpler to solve by adding more degrees of freedom than occur in nature. In addition, Belitsky has become adept in a powerful technique called integrability, in which QCD and similar theories can be mathematically related to the physics of systems like ferromagnets and other "spin-chains". Meanwhile, Lebed is studying "holographic QCD," which is based upon an idea from string theory, that QCD and related strongly-interacting theories can be related to weakly-interacting gravity on a curved space. Each of Belitsky and Lebed will mentor a Ph.D. student in these project areas.