Phenomenology from lattice QCD and collider physics

晶格 QCD 和对撞机物理的现象学

• 批准号: ST/X000605/1
• 负责人: Christoph Englert
• 金额: $ 71.26万
• 依托单位: University of Glasgow
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FX000605%2F1
• 关键词: Phenomenology; lattice; QCD; collider; physics

The Glasgow theory group has a strong reputation in studies of the subatomic world, and pushing forward our understanding of how it works. This is aimed at uncovering the fundamental constituents of matter and the nature of the interactions that operate between them. There are two approaches to this, and we will use both of them. One is to perform very accurate calculations within the theoretical framework of the Standard Model that we believe correctly describes the particles that we have seen so far and the strong, weak and electromagnetic forces of Nature. Discrepancies between these accurate calculations and what is seen in experiments will then point the way to a deeper theory that describes fundamental particle physics more completely. The second method is concerned with what we might see at CERN's Large Hadron Collider if one or other of the suggested deeper theories is correct, alongside interpretations of particle physics measurements without such theoretical prejudice. We must make sure that we optimise the analysis of the experiments there to learn as much as possible. Accurate calculations in the Standard Model have foundered in the past on the difficult problem of how to handle the strong force. This force is important inside particles that make up the atomic nucleus, the proton and neutron and a host of similar particles called hadrons produced in high energy collisions. The constituents of these particles are quarks, and they are trapped inside hadrons by the behaviour of the strong force. This 'confinement' of quarks makes calculations of the effect of the strong force on the physics of hadrons very challenging. It can be tackled, however, using the numerical technique of lattice QCD, which Glasgow has been instrumental in turning into a precision tool. Glasgow continues to lead progress and here we propose calculations that will predict more accurately how hadrons decay from one type to another via the weak force. The comparison with experiment will then allow us to push down uncertainties in the parameters of the weak force that allow for violations of symmetry between matter and antimatter. We also plan to calculate accurately the tiny effect of the strong force on the magnetic moment of the muon ahead of a new experimental determination of this quantity that aims to find out for sure whether it agrees with the Standard model or not. The Glasgow team will also investigate theories that go beyond the Standard Model and test them with LHC data. The heaviest known particles, the Higgs boson and the top quark, are believed to be fundamental and can be harbingers of new dynamics. We must therefore undertake a comprehensive precision programme to measure their properties to the highest attainable precision. New physics may show up by subtly modifying these properties and we will devise ways of looking for these effects alongside other evidence for new physics. We will study particle properties by means of general, model-independent methods, which also make use of artificial intelligence to maximise sensitivity. This approach will enable us to connect our findings transparently with precise measurements of the aforementioned hadrons, which are sensitive to the presence of new particles and interactions. We will also examine specific new physics models, such as theories of Grand Unification, which unify the three forces together as one single force. We will determine how these exciting and fundamental theories affect the particle properties described above and thereby confront them with LHC observations. Experimental studies on the Higgs boson and top quarks are being led by the Glasgow ATLAS group and we will coordinate with them to uncover the fundamental truths of the universe. The next few years will be a very exciting time for theoretical particle physics and Glasgow aims to be at the forefront of this work, preparing for the next Large Hadron Collider data taking runs.

格拉斯哥理论小组在亚原子世界的研究方面享有盛誉，并推动了我们对它如何工作的理解。这是为了揭示物质的基本组成和它们之间相互作用的性质。有两种方法，我们将使用这两种方法。一个是在标准模型的理论框架内进行非常精确的计算，我们相信标准模型正确地描述了我们迄今为止所看到的粒子以及自然界的强、弱和电磁力。这些精确的计算和实验中看到的结果之间的差异将为更完整地描述基本粒子物理学的更深入的理论指明道路。第二种方法关注的是，如果所提出的一个或另一个更深层次的理论是正确的，我们可能会在欧洲核子研究中心的大型强子对撞机上看到什么，以及在没有这种理论偏见的情况下对粒子物理测量的解释。我们必须确保我们优化那里的实验分析，以尽可能多地学习。过去，标准模型的精确计算在如何处理强作用力的难题上失败了。这种力在构成原子核、质子和中子的粒子内部很重要，在高能碰撞中产生了大量类似的粒子，称为强子。这些粒子的成分是夸克，它们被强作用力的行为困在强子内部。夸克的这种“禁闭”使得计算强作用力对强子物理学的影响非常具有挑战性。然而，它可以用格点QCD的数值技术来解决，格拉斯哥在把它变成一个精确的工具方面发挥了重要作用。格拉斯哥继续引领进展，在这里，我们提出的计算，将更准确地预测强子如何通过弱力从一种类型衰变到另一种类型。与实验的比较将使我们能够降低弱力参数的不确定性，这种不确定性允许物质和反物质之间的对称性被破坏。我们还计划精确计算强作用力对μ子磁矩的微小影响，然后对这个量进行新的实验测定，以确定它是否符合标准模型。格拉斯哥团队还将研究超越标准模型的理论，并用大型强子对撞机的数据进行测试。已知最重的粒子希格斯玻色子和顶夸克被认为是基本粒子，可能是新动力学的预兆。因此，我们必须进行全面的精密计划，以达到最高的精度来测量它们的属性。新的物理学可能会通过巧妙地修改这些性质而出现，我们将设计出寻找这些效应以及新物理学的其他证据的方法。我们将通过一般的，独立于模型的方法来研究粒子特性，这些方法还利用人工智能来最大限度地提高灵敏度。这种方法将使我们能够透明地将我们的发现与上述强子的精确测量联系起来，这些强子对新粒子和相互作用的存在很敏感。我们还将研究特定的新物理模型，如大统一理论，它将三种力统一为一种力。我们将确定这些令人兴奋的基本理论如何影响上述粒子性质，从而用LHC观测来对抗它们。对希格斯玻色子和顶夸克的实验研究正在由格拉斯哥ATLAS小组领导，我们将与他们协调，以揭示宇宙的基本真理。未来几年将是理论粒子物理学非常激动人心的时刻，格拉斯哥的目标是站在这项工作的最前沿，为下一个大型强子对撞机数据采集运行做准备。