Coordination Funds

量子色动力学（QCD）是描述强核力的标准模型的一部分，强核力将夸克和胶子结合在强子内部。该理论限制了强子的组成，这些成分在实验中从未被直接观察到。因此，将实验现象与强耦合量子场论联系起来仍然极具挑战性。特别是，禁闭的性质和禁闭胶子的物理特征仍然知之甚少。在新千年之初的实验中发现了一系列完全出乎意料的狭窄共振，称为X、Y和z，对粲夸克的研究经历了一场革命。粲夸克是一个包含粲夸克-反夸克对的系统。这些共振的性质尚不清楚。类似地，最近人们对胶球（主要由受限胶子构成的强子）的兴趣又恢复了。最近和计划中的实验提出了许多理论的物理问题：A)组成胶子是否在调和体中发挥重要作用并产生可观察到的后果？b) QCD能预测胶球的存在吗？c)它们是否可以通过实验搜索中看到的共振来识别？晶格QCD是一种理论技术，可以直接与依赖于大规模蒙特卡罗计算的QCD物理联系起来。然而，QCD中涉及组成胶子的许多问题仍未得到解决。由于在采样过程中包含夸克动力学的计算成本很高，同时用于研究受限胶子的蒙特卡罗估计的统计波动也很严重，因此这些计算出现了困难。该项目的两个主要目标是：1。开发和优化蒙特卡罗计算中相关函数方差减少的新技术，并具有强大的数学基础；2. 测试并开始利用这些方法来回答问题a)到c)。提出的研究单位将通过结合晶格QCD物理学家和数值分析师的跨学科专业知识来开发所需的新方法。在开发了一个先进的框架来解决a) c)计算问题之后，该小组将详细研究QCD的胶球和调和态，使用这些领域来测试和优化新方法，同时为下一代晶格计算做准备。新方法将被有效地传播，以确保它们在未来的晶格QCD计算中得到广泛的应用。这项研究将导致理论物理和应用数值分析学科之间思想的交叉融合，在大规模物理计算中测试分子动力学和线性代数的发展。研究股将促进这些学科之间更密切的合作。研究结果将与有效的场理论一起有助于理解当前和未来的实验。

Quantum Chromodynamics (QCD) is the sector of the standard model describing the strong nuclear force, which binds quarks and gluons inside hadrons. The theory confines the constituents of hadrons, which are never observed directly in experiment. As a result, connecting experimental phenomena to the strongly coupled quantum field theory remains extremely challenging. In particular, the nature of confinement and physical signatures of confined gluons remain very poorly understood.The study of charmonium, a system containing a charm quark-anti-quark pair underwent a revolution after a number of entirely unexpected narrow resonances called the X, Y and Zs were discovered by experiments at the start of the new millennium. The nature of these resonances is still unclear. Similarly, interest in glueballs, hadrons made predominantly of confined gluons, has revived recently. A number of physics questions for theory are raised by recent and planned experiments: a) Do constituent gluons play an important role in the charmonium sector with observable consequences? b) Does QCD predict the existence of glueballs? c) Can they be identified with resonances seen in an experimental search?Lattice QCD is a theoretical technique enabling a direct link with QCD physics which relies on large-scale Monte Carlo calculations. Many problems involving constituent gluons in QCD remain unsolved, however. Difficulties arise in these calculations as the computational cost to include the quark dynamics in the sampling process is high, while at the same time the statistical fluctuations in the resulting Monte Carlo estimates used to study confined gluons are severe. The two main objectives of this project are: 1. to develop and optimise new techniques for variance reduction of correlation functions in Monte Carlo calculations with a robust mathematical foundation; 2. to test and begin exploiting these methods to answer the questions a) to c).The Research Unit proposed will develop the new methods needed by combining the inter-disciplinary expertise of lattice QCD physicists and numerical analysts. After developing an advanced framework to address the questions a)-c) computationally, the group will study the glueballs and charmonium states of QCD in detail, using these arenas to test and optimise the new methods while preparing for the next generation of lattice calculations. The new methods will be disseminated effectively to ensure they become widely used in as broad a range of future lattice QCD calculations as applicable.This research will lead to a cross-fertilisation of ideas between the disciplines of theoretical physics and applied numerical analysis, testing developments in molecular dynamics and linear algebra in large-scale physics computations. The Research Unit will foster closer collaboration between these disciplines. The outcome of the research will contribute along with effective field theories to the understanding of present and future experiments.