Nuclear Physics Consolidated Grant

大约98%的核子质量，也就是可见宇宙的质量，来自于它们的组成部分夸克和胶子之间的相互作用。希格斯机制赋予裸夸克质量，但只占核子质量的一小部分。夸克在介子和重子中的禁闭是它们基本相互作用的直接结果。强核力的场论，即量子色动力学（QCD），现在已经很好地建立起来了，但是上面描述的现象不能从QCD拉格朗日量来理解;它们是从这些相互作用的独特复杂性中产生的涌现性质。量子色动力学在核子和原子核的质量尺度上还很难处理，因此在这些能量下物质的基本性质的清晰图像还不存在。然而，这种情况将发生变化，在未来十年的理论和实验发展预计将彻底改变我们对QCD和标准模型背景下的核物质的理解。我们有一个雄心勃勃的工作计划，包括从现有主题开发研究计划，最近开放的新物理测量的可能性，以及从以前获得的数据完成物理项目。我们的计划将建立在我们以前的综合赠款工作的基础上，我们将利用人力和设备投资，在世界顶级设施的最高水平上解决我们领域的当前问题。科学计划的挑战被几个关键问题所概括，我们将它们归类在一起，因为它们大致符合我们定义的主题：* 将夸克和胶子限制在强相互作用粒子（强子）中的机制是什么？质子和中子的结构是什么？强子是如何得到它们的质量和自旋的？* 我们能从夸克-夸克相互作用理解强子的激发谱吗？* 奇异强子（多夸克态、混合介子和胶球）存在吗？* QCD如何产生核力？* 核物质的状态方程是什么？* 暗物质的本质是什么？我们将通过在以下两个世界领先的实验室开展领先的实验项目来解决这些问题：* 美国弗吉尼亚州纽波特纽斯的杰斐逊实验室（JLab）* 德国美因茨的MAMI：

Approximately 98% of the mass of nucleons, and therefore of the visible universe, emerges from the interactions among their constituents, the quarks and gluons. The Higgs mechanism, which gives mass to the bare quarks, is responsible for only a small fraction of the nucleon mass. The confinement of quarks within mesons and baryons is a direct consequence of their fundamental interactions. The field theory of the strong nuclear force, Quantum Chromodynamics (QCD), is now well established, and yet the phenomena described above cannot be understood from the QCD Lagrangian; they are emergent properties that arise from the unique complexity of these interactions. QCD is as yet intractable at the mass scale of nucleons and nuclei, so a clear picture of the fundamental nature of matter at these energies does not yet exist. However, this situation is set to change, and both theoretical and experimental developments in the coming decade are expected to revolutionise our understanding of nuclear matter within the context of QCD and the Standard Model. We have an ambitious plan of work that encompasses the development of research programmes from existing themes, possibilities for new physics measurements that have opened up recently, and the completion of physics projects from data that has been previously obtained. Our programme will build on the work of our previous consolidated grant and we will exploit the investment in manpower and equipment to address the current issues in our field at the highest possible level, at the world's top facilities. The challenges for the science programme are encapsulated by several key questions, which we group together as they roughly match the themes we have defined:* What is the mechanism for confining quarks and gluons in strongly interacting particles (hadrons)?* What is the structure of the proton and neutron, and how do hadrons get their mass and spin? * Can we understand the excitation spectra of hadrons from the quark-quark interaction? * Do exotic hadrons (multiquark states, hybrid mesons and glueballs) exist? * How do nuclear forces arise from QCD? * What is the equation of state of nuclear matter? * What is the nature of dark matter?We will address these questions by leading experimental programmes at two of the world's leading facilities:* Jefferson Lab, Newport News, Virginia, USA (JLab)* MAMI, Mainz, Germany: