The University of Liverpool, Department of Physics Particle Physics Rolling Grant

描述束缚基本粒子使我们生活的世界的力的理论未能捕捉到质量现象，最自然地只对无质量的基本粒子起作用。在电弱统一能标度下，弱核力和电磁核力表现出相同的强度，这一事实与载力的W和Z粒子的质量有关，这是“弱”力明显减弱的根本原因，这一新物理解决了这个问题。在这种特征质量/能量尺度下的“新物理学”通常被认为与质量略高于W和Z的希格斯粒子的存在有关。然而，即使这是正确的情况，也存在强有力的理论论据来支持其他接近能量尺度的现象。所有这些都为建造大型强子对撞机及其物理计划的一个方面--利用高能碰撞直接产生新粒子--提供了一个主要动机。阿特拉斯在利物浦组装了其跟踪探测器的一个主要部件，该公司正在寻找这样的“新物理学”，但为了确保发现，必须在大型强子对撞机的高能碰撞中极好地理解已知物理学--“标准模型”的预测。这是关键的第一步，利物浦正在强调这一点，因为它对强相互作用物理和质子结构的理解令人印象深刻。另一种可以发现偏差的方式是在较低能量下的微妙效应，例如在含有b夸克的粒子的衰变中，b夸克是最大的夸克，具有可测量的寿命。这就是大型强子对撞机实验的目标，在该实验中，大型强子对撞机产生的短寿命粒子的探测依赖于顶点定位器(VELO)探测器，利物浦为该探测器建造了所有模块。利物浦的物理学家在这项实验的几个方面发挥了重要作用，包括与探索稀有标准模型过程有关的研究。在发现与标准模型的偏差方面，另一个被证明是非常有成效的领域是中微子的性质。这些可以通过中微子振荡实验来探索，这些实验对中微子质量(直到十年前还被认为是零)以及不同类型的中微子如何相互转换都很敏感。日本J-PARC实验室正在生产的强流光束，是中微子和反中微子之间的不对称理论的理想试验场，这些理论可能有助于产生我们在今天的宇宙中看到的反物质不对称(据我们所知，在宇宙中，所有反物质已经湮灭)。在所有这些方案中，基于这些试验的未来充满活力，我们在旨在升级以更好地利用这些独特设施的计划和研究中发挥关键作用。在大型强子对撞机上，加速器的改进将导致大部分探测器的重建。特别是，可能需要更高的辐射硬度，我们在辐射硬硅探测器方面享有世界领先的声誉。其他方面需要先进的材料和低质量的结构、新颖的互连技术和微电子技术的发展。这些都是我们带来独特技能的领域，目前提供给实验的探测器已经证明了这一点。除了研究硅传感器(条状和像素)外，我们还在研究基于液态Ar的新型探测器，以及磁卡计的组合概念。较长期的未来显然将包括在现有设施上安装新的加速器和新的加速器部件。我们特别适合通过我们在Cockcroft研究所的领导角色做出贡献，该研究所的主任是利物浦教授。利物浦在仿制药研发方面有着悠久的传统，这导致了新技术的重大发展。我们尽可能与英国工业界密切合作，以确保最广泛地传播新成果。

The theories describing the forces binding fundamental particles to make the world we live in fail to capture the phenomenon of mass, working most naturally only for massless fundamental particles. The problem is solved by new physics at the electroweak unification energy scale, where the weak nuclear force and that of electromagnetism are found to show the same strength, a fact associated with the mass of the force-carrying W and Z particles being the root cause of the apparent weakness of the 'weak' force. The 'new physics' at this characteristic mass/energy scale is often thought to be related to the existence of a Higgs particle with mass just above that of the W and Z. However, even if this is the correct scenario, strong theoretical arguments exist for other phenomena, close in energy scale. All of this provides a major motivation for building the LHC and for one aspect of its physics programme, the search, using high energy collisions, for direct production of new particles. ATLAS, with a major component of its tracking detector assembled at Liverpool, is searching for such 'new physics', but to be sure of a discovery, the predictions of the known physics, the 'Standard Model', have to be understood extremely well in the high energy collisions of the LHC. This is a key first step and one that Liverpool is emphasising with its impressive understanding of strong interaction physics and proton structure. Another way deviations can be found is in subtler effects at lower energies, for example in the decays of particles containing the b-quark, the most massive quark with a measurable lifetime. This is the target of the LHCb experiment, where the detection of short lived particles produced at the LHC relies on the Vertex Locator (VeLo) detector for which all the modules were built at Liverpool. Liverpool physicists are playing major roles in several aspects of this experiment, including studies relating to exploration of rare Standard Model processes. Another area which has proved very fruitful in finding deviations from the Standard Model is in the properties of neutrinos. These can be explored through 'neutrino oscillation' experiments, sensitive to both neutrino masses (thought to be zero until a decade ago) and how different types of neutrinos can inter-convert. The intense beam being produced at the J-PARC laboratory in Japan is the ideal testing ground for ideas that asymmetries between neutrinos and anti-neutrinos may have helped produce the matter anti-matter asymmetry we see in today's Universe (where, as far as we can tell, all the anti-matter has annihilated away). In all these programmes, there is a lively future building on these experiments and we play a key role in plans and research aimed at upgrades to allow better exploitation of these unique facilities. At the LHC, improvements to the accelerator will lead to the rebuilding of large parts of the detectors. In particular, much greater radiation hardness may be needed and we enjoy a world-leading reputation in radiation hard silicon detectors. Other aspects require advanced materials and low mass structures, novel interconnect technologies and microelectronics developments. These are all areas where we bring unique skills, already demonstrated in the detectors provided to current experiments. In addition to work on silicon sensors (both strip and pixels), we are working on novel liquid argon based detectors, and on a combined magnet-calorimeter concept. The longer term future clearly will involve new accelerators and new accelerator components on existing facilities. We are particularly well placed to contribute through our lead role in the Cockcroft Institute whose Director is a Liverpool professor. Liverpool enjoys a long tradition of generic research and development which leads to major developments in new technologies. We work closely with UK industry wherever possible to ensure the widest possible dissemination of novel results