Nuclear Physics from QCD

我们这个时代的一个重要的智力挑战是理解强子和核结构的复杂性是如何从夸克和胶子的QCD描述中产生的。在没有解决QCD的非微扰方法的情况下，人们可以用有效场论（EFT）来描述强子物理和核物理。EFT的基本思想是发展一种在强子和核系统中大量存在的、在广泛分离的尺度中的比值的微扰展开。在这个展开式中出现的待定参数可以拟合到数据中，或者使用对称性和大Nc方法进行约束，并最终使用格点QCD进行计算。这种方法导致了丰富的核理论和实验之间的相互作用，目前是不可缺少的非物理晶格QCD模拟外推到自然界。我们建议发展强子和核物理与QCD之间的新联系，并促进格点QCD和原子核之间的第一个联系，使用有效的量子场论约束的QCD对称性。我们的目标是：（i）进一步发展核理论与实验之间的活跃关系，并继续目前正在进行的开拓性努力，利用晶格QCD了解简单核的基本性质。我们建议在低能量下研究涉及两体和三体系统的外部探针的过程，并研究用于提取核子参数的同位旋破坏的相关性。开发一个质量独立的监管机构的问题-像尺寸正则化-核EFT将继续。我们打算发展一种用于超核物理的EFT，它将有助于描述奇异物质和从格点QCD中提取超核观测值。重强子势为研究格点QCD中的中程核力提供了理论实验室。因此，我们建议使用EFT研究两个重介子和其他简单系统之间的长距离势。(ii)开发新的工具，使即将到来的格点QCD数据外推。我们建议研究有限格点间距修正在重子和重介子扇区中的作用。有限体积效应的作用将被研究的目的外推强子可观的无限体积，并作为一种工具，从晶格模拟提取S-矩阵元素。(iii)我们打算研究奇异强子手征对称性的代数相关性，包括最近观察到的“五夸克”，并进一步理解手征对称性在以下方面的作用：（a）约束夸克-强子对偶性和（B）解密激发态介子和重子的大Nc结构。该项目的长期目标是发展一种与QCD一致的强子和原子核的描述，并对理论错误进行严格的解释。我们希望我们的研究能够产生重大影响，无论是在将核物理纳入标准模型的有效场论中，还是作为全球努力的一部分，将强子物理和核物理置于理论控制之下，以寻找标准模型之外的物理。这个项目标志着新罕布什尔州大学核理论项目的开始。该方法的普遍性使得所提出的研究理想的研究生和本科生的教育。

An important intellectual challenge of our time is to understand how the complexities of hadronic and nuclear structure arise from a QCD description in terms of quarks and gluons. In the absence of nonperturbative methods for solving QCD, one may formulate an effective field theory (EFT) to describe hadronic and nuclear physics. The basic idea of EFT is to develop a perturbative expansion in ratios of widely separated scales, which are plentiful in hadronic and nuclear systems. The undetermined parameters that appear in this expansion can be fit to data, or constrained using symmetries and large-Nc methods, and ultimately computed using lattice QCD. This methodology has led to a rich interplay between nuclear theory and experiment and is currently indispensable to the extrapolation of unphysical lattice QCD simulations to nature. We propose to develop new links between hadronic and nuclear physics and QCD, and to facilitate the first links between lattice QCD and nuclei, using effective quantum field theories constrained by QCD symmetries. Our objectives are: (i) To further develop the vibrant relationship between nuclear theory and experiment and to continue the pioneering efforts currently underway to understand basic properties of simple nuclei using lattice QCD. We propose to study processes involving external probes of two- and three-body systems at low energies and to investigate the relevance of isospin violation for the extraction of nucleon parameters. The problem of developing a mass-independent regulator - like dimensional regularization - for nuclear EFT will be pursued. We intend to develop an EFT for hypernuclear physics which will aid in describing strange matter and in extracting hypernuclear observables from lattice QCD. Heavy-hadron potentials offer a theoretical laboratory for exploring the intermediate-range nuclear force in lattice QCD. We therefore propose to study the long-distance potential between two heavy mesons and other simple systems using EFT. (ii) To develop new tools to allow extrapolation of forthcoming lattice QCD data. We propose to investigate the role of finite lattice spacing corrections both in the baryon and heavy meson sectors. The role of finite-volume effects will be studied both for the purpose of extrapolating hadronic observables to infinite volume and as a tool to extract S-matrix elements from lattice simulations. (iii) We propose to study the algebraic relevance of chiral symmetry for strange hadrons, including the recently observed "pentaquark" and to further understand the role of chiral symmetry in: (a) constraining quark-hadron duality and (b) decrypting the large-Nc structure of the excited mesons and baryons. The long-term goal of this project is to develop a description of hadrons and nuclei that is consistent with QCD and which has a rigorous accounting of theoretical errors. We expect our research to have significant impact, both in bringing nuclear physics into the fold of effective field theories of the standard model, and as part of the global effort to bring hadronic and nuclear physics under theoretical control for the purpose of searching for physics beyond the standard model. This project marks the beginning of a program in nuclear theory at the University of New Hampshire. The universal character of the methodology renders the proposed research ideal for the education of graduate and undergraduate students.