Proposal for IPPP (UK National Phenomenology Institute), 2020-2023

粒子物理学的研究告诉我们在非常小的尺度上物质的本质。当我们沿着长度尺度往下走，低于原子的长度尺度10^（-10）米，超过原子核的长度尺度10^（-15）米，我们就进入了粒子物理学的领域。在这个领域中，有三种明确的相互作用。首先是强相互作用，它负责将夸克和胶子结合，产生质子、中子和其他统称为强子的粒子。第二种是电弱相互作用。电弱相互作用既造成了来自物质的光子辐射，也造成了弱力载体W和Z玻色子的辐射，这是1983年在欧洲核子研究中心发现的。第三，希格斯玻色子的相互作用。希格斯玻色子是2012年在欧洲核子研究中心发现的。所有这些成分的相互作用都由一个数学结构控制，这个数学结构被称为电磁、弱和强相互作用的标准模型（SM）规范理论。到目前为止，这一理论经受住了各种加速器带来的所有挑战，其中最新、最具活力的是大型强子对撞机。SM被证实了——电磁和弱相互作用的统一被证明和测试到了每英里的一部分。强相互作用效应已测试到百分比水平。夸克，强子的成分，有六种不同的类型，被称为味道。在形成SM的整体结构时，风味现象的贡献与计量原则一样多，正是风味的存在赋予了SM家族和世代结构。在夸克领域，味道现象的SM描述和混合和CP违反的CKM图像现在在几个百分点的水平上得到了验证。在轻子领域，轻子的味道是电子、μ子和tau以及它们相关的中微子。对中微子振荡的观察，以及中微子具有质量的结论，要求扩展SM。对带电轻子和中性轻子的详细检查越来越重要。自2015年以来，大型强子对撞机（LHC）一直在以比以往更高的能量加速和碰撞质子，接近14 TeV的设计能量。这种高能量探测的距离比以往任何时候都要短得多。大型强子对撞机的高能量范围也将允许对希格斯玻色子的详细研究和对TeV尺度物理的探索。然而，大型强子对撞机的实验比以往任何粒子物理实验都要复杂得多。确定TeV尺度下的物理性质需要实验家和理论家之间的密切合作。在理论方面，需要对SM过程进行高精度计算，以从SM背景中区分可能的新物理信号。为了解开tev尺度物理学的潜在结构，新物理学的可能线索需要与超越SM的不同物理模型进行比较。IPPP已经与英国和国际实验团体建立了密切的联系，并且完全有能力帮助英国最大限度地为理解LHC数据做出贡献。在规划和设计下一代粒子物理实验方面也有很大的努力。IPPP将继续在评估物理潜力和设计未来加速器方面发挥作用。未来十年将是我们对微观世界理解的关键时期。IPPP将解决以下基本问题：电弱对称性破缺、时空结构、风味物理和CP违反、中微子和轻子风味违反，以及粒子物理学如何与天体物理学和宇宙学联系起来。

Particle physics research informs us about the nature of matter on very small scales. As we step down the length scales below the length scale of the atom, 10^(-10) meters, and past the length scale of the atomic nucleus, 10^(-15) meters, we enter the realm of particle physics. In this realm there are three well identified interactions. First, the strong interactions, which are responsible for the binding of quarks and gluons to produce protons, neutrons and other particles collectively called hadrons. Second, the electroweak interactions, responsible both for the radiation of photons (light) from matter and the radiation of the carriers of the weak force, the W and Z bosons, discovered at CERN in the 1983. Third, the interactions of the Higgs bosons. The Higgs boson was discovered at CERN in 2012. The interactions of all of these ingredients are controlled by a mathematical structure, known as the Standard Model (SM) gauge theory of electromagnetic, weak and strong interactions. This theory has so far withstood all the challenges posed by various accelerators, of which the latest and most energetic is the LHC. The SM is confirmed - with the unification of electromagnetism and weak interactions proved and tested to one part per mille. Strong interaction effects have been tested to the percent level.The quarks, the ingredients of the hadrons, come in six different types which are referred to as flavours. Flavour phenomena have contributed as much as the gauge principle in shaping the overall structure of the SM and it is the existence of flavours that gives the SM its family and generation structure. In the quark sector the SM description of flavour phenomena and the CKM picture of mixing and CP violation is now verified at the few per cent level. In the lepton sector, the flavours of leptons are the electron, the muon and the tau and their associated neutrinos. The observation of neutrino oscillations, and the consequence that neutrinos have mass, calls for an extension of the SM. Detailed examination of the charged and neutral leptons is of increasing importance.Since 2015, the Large Hadron Collider (LHC) has been accelerating and colliding protons at much higher energies than ever before, close to the design energy of 14 TeV. This higher energy probes much shorter distance scales than ever before. The high energy reach of the LHC will also allow the detailed study of the Higgs boson and exploration of TeV scale physics. However, the LHC experiments are significantly more complex than any previous particle physics experiment. Identifying the nature of physics at the TeV scale will require intense collaborative efforts between experimentalists and theorists. On the theoretical side, high-precision calculations of SM processes are needed to distinguish possible signals of new physics from SM backgrounds. Possible hints of new physics need to be compared with different models of physics beyond the SM in order to disentangle the underlying structure of TeV-scale physics. The IPPP has already established close connections with the UK and international experimental groups and is perfectly placed to help maximise the UK contribution to understanding the LHC data.There is also a strong effort in planning and designing the next generation of particle physics experiments. The IPPP will continue its role in assessing the physics potential and the design of future accelerators. The next decade promises to be pivotal in our understanding of the microscopic world. The IPPP will address fundamental questions about electroweak symmetry breaking, the structure of space-time, flavour physics and CP violation, neutrinos and lepton-flavour violation, and how particle physics connects with astrophysics and cosmology.