Experimental Particle Physics Research at High Energies

世纪的主要学术成就之一是粒子物理学标准模型（SM）的发展。这个模型成功地将当时已知的所有基本粒子分类为具有类似量子性质的层次结构。到目前为止，这个模型的有效性被大型强子对撞机（LHC）发现的希格斯玻色子所证实。 然而，目前存在的标准模型留下了许多关于宇宙的问题，包括为什么希格斯质量具有它的价值等基本问题。 LHC的紧凑μ子螺线管（CMS）实验的主要功能之一是发现标准模型之外的新物理，该实验仍然是瑞士日内瓦附近的CERN实验室的首要能源前沿粒子加速器。这个项目将分析CMS实验的数据，寻找超出标准模型的信号。该奖项将影响三个广泛的领域：1）升级CMS探测器的高技术组件2）劳动力开发和推广到更广泛的社区3）促进可能在LHC发现新物理的分析技术。凭借东北大学强大的合作教育计划，该小组将继续定期让本科生参与欧洲核子研究中心为期六个月的有意义的项目。PI还将继续参与波士顿地区QuarkNet小组（现在已经是第14年），在那里他们能够接触到当地的高中教师和学生。小组成员还通过向粒子物理学以外的观众进行讲座和演讲，与更广泛的公众分享发现和结果的兴奋和知识。通过该奖项资助的工作将寻找一些新的粒子物理领域，其中有超越SM物理的理论模型。发现轻子夸克将提供夸克扇区和轻子扇区之间的联系，并有助于解释为什么这两个扇区都包含三代物质。探测到希格斯玻色子的大量不可见衰变将回答有关电弱对称性破缺性质的重要问题。希格斯玻色子的不可见衰变是各种超越标准模型物理学理论的标志。在这些实验中，希格斯玻色子可以与新的重粒子相互作用，这些重粒子衰变成通常无法被实验检测到的粒子（如中微子）。希格斯玻色子不可见的衰变率的限制也为暗物质的模型提供了限制。该项目的研究还包括测量标准模型过程的微分截面测量，如ZZ生产和W+射流生产，这些过程对新物理学具有敏感性。这些研究与新物理学研究紧密结合，因为它们测量的过程是特定目标搜索的重要背景。在这些通道中的任何一个中存在信号都将对我们对粒子物理的理解产生深远的影响，而确定它的缺失将对粒子物理标准模型之外的物理模型提供重要的约束。

One of the major intellectual achievements of the 20th century was the development of the Standard Model (SM) of particle physics. This model succeeded in classifying all the elementary particles known at the time into a hierarchy of groups having similar quantum properties. The validity of this model to date was confirmed by the discovery of the Higgs boson at the Large Hadron Collider (LHC). However, the Standard Model as it currently exists leaves open many questions about the universe, including such fundamental questions as to why the Higgs mass has the value it has. One of the primary functions of the Compact Muon Solenoid (CMS) experiment at the LHC, which remains the premier Energy Frontier particle accelerator, operating at the CERN laboratory near Geneva Switzerland, is to discover new physics beyond the Standard Model. This project will analyze data from the CMS experiment looking for signals of beyond the Standard Model. The work that will be accomplished with this award will impact three broad areas: 1) Upgrading the highly technical components of the CMS detector 2) workforce development and outreach to the broader community and 3) furthering the analysis techniques that might well discover new physics at the LHC. With the strong cooperative education program at Northeastern University, the group will continue to routinely involve undergraduates in meaningful six-month projects at CERN. The PIs will also continue their involvement with the Boston Area QuarkNet group (now in its 14th year) where they are able to reach out to local high school teachers and their students. The group members also share the excitement and knowledge of the discoveries and results with the broader public through lectures and presentations to audiences outside of particle physics. The work funded through this award will search for a number of new particle physics sectors where there are theoretical models of beyond the SM physics. A discovery of leptoquarks would provide a link between the quark sector and the lepton sectors and help to explain why both sectors contain three generations of matter. Detection of substantial invisible decays of the Higgs boson would answer important questions about the nature of electroweak symmetry breaking. Invisible decays of the Higgs are a signature of various beyond the standard model physics theories. In these, the Higgs can interact with new heavy particles which decay into particles that are usually not detected by the experiment (like neutrinos). Limits on the invisible decay rate of the Higgs boson also provide constraints on models of Dark Matter. This project's studies also include measurements of the differential cross section measurements of Standard Model processes, such as ZZ production, and W+jets production, that have sensitivity to new physics. These studies are tightly coupled with the new physics searches because the processes they measure are important backgrounds to the specific searches targeted. The presence of a signal in any of these channels would have profound impact on our understanding of particle physics, while establishing its absence would provide important constraints on models of physics beyond the Standard Model of particle physics.