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

描述束缚基本粒子的力以构成我们生活的世界的理论未能捕捉到质量现象，最自然地只适用于无质量的基本粒子。这个问题由电弱统一能尺度的新物理学解决，其中发现弱核力和电磁力显示出相同的强度，这一事实与携带力的W和Z粒子的质量有关，这是“弱”力明显弱的根本原因。这种特征质量/能量尺度下的“新物理学”通常被认为与希格斯粒子的存在有关，希格斯粒子的质量刚好高于W和z。然而，即使这是正确的情况，也存在着其他接近能量尺度的现象的强有力的理论论据。所有这些都为建造大型强子对撞机提供了主要动力，并为其物理项目的一个方面提供了动力，即利用高能碰撞直接产生新粒子。ATLAS，其跟踪探测器的一个主要组件组装在利物浦，正在寻找这样的“新物理”，但为了确定一个发现，已知物理的预测，“标准模型”，必须在大型强子对撞机的高能碰撞中得到非常好的理解。这是关键的第一步，也是利物浦对强相互作用物理和质子结构的深刻理解所强调的一步。另一种发现偏差的方法是在较低能量的更微妙的影响中，例如在含有b夸克的粒子的衰变中，b夸克是寿命可测量的最大的夸克。这是LHCb实验的目标，LHC产生的短寿命粒子的检测依赖于顶点定位器（VeLo）探测器，所有模块都是在利物浦建造的。利物浦的物理学家在这个实验的几个方面扮演着重要的角色，包括与探索罕见的标准模型过程有关的研究。在发现与标准模型的偏差方面，另一个被证明非常富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，对中微子质量（直到十年前被认为是零）和不同类型的中微子如何相互转换都很敏感。在日本的J-PARC实验室产生的强光束是一个理想的试验场，用于验证中微子和反中微子之间的不对称可能有助于产生我们今天在宇宙中看到的物质反物质不对称（据我们所知，在宇宙中，所有的反物质都已经湮灭了）。在所有这些项目中，这些实验都有一个充满活力的未来，我们在旨在升级的计划和研究中发挥关键作用，以便更好地利用这些独特的设施。在大型强子对撞机中，对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结构，新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，已经在提供给当前实验的探测器中得到了证明。除了硅感测器（包括条形感测器和像素感测器）之外，我们也在研究新型液态氩气侦测器，以及结合磁体量热计的概念。长远来看，显然将涉及在现有设施上安装新的加速器和新的加速器组件。通过我们在科克罗夫特研究所的领导作用，我们特别有能力做出贡献，该研究所的主任是一位利物浦教授。利物浦在通用研究和开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