Experimental Particle Physics Research at High Energies

20世纪的主要智力成就之一是粒子物理标准模型(SM)的发展。这个模型成功地将当时已知的所有基本粒子归入具有相似量子性质的群组的层次中。在大型强子对撞机(LHC)上发现的希格斯玻色子证实了这个模型到目前为止的有效性。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这样的基本问题。大型强子对撞机上的紧凑型介子螺线管(CMS)实验的主要功能之一是发现标准模型以外的新物理。大型强子对撞机仍然是主要的能源前沿粒子加速器，在瑞士日内瓦附近的欧洲核子研究中心实验室运行。这个项目将分析来自CMS实验的数据，寻找超越标准模型的信号。该奖项将完成的工作将影响三个广泛的领域：1)升级CMS探测器的高技术部件；2)劳动力发展和扩展到更广泛的社区；3)促进分析技术，很可能在大型强子对撞机上发现新的物理。通过东北大学强大的合作教育项目，该组织将继续让本科生定期参与CERN为期六个月的有意义的项目。PIS还将继续参与波士顿地区QuarkNet小组(现已进入第14个年头)，在那里他们能够接触到当地高中教师和他们的学生。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。这项由该奖项资助的工作将寻找一些新的粒子物理部门，其中有Beyond SM物理的理论模型。轻夸克的发现将提供夸克部门和轻子部门之间的联系，并有助于解释为什么这两个部门都包含三代物质。探测到希格斯玻色子实质上不可见的衰变将回答有关弱电对称破缺本质的重要问题。希格斯粒子的不可见衰变是各种超越标准模型物理理论的标志。在这些粒子中，希格斯可以与新的重粒子相互作用，这些粒子衰变成实验通常检测不到的粒子(如中微子)。对希格斯玻色子不可见衰减率的限制也限制了暗物质的模型。该项目的研究还包括对对新物理敏感的标准模型过程的微分截面测量，如ZZ生产和W+喷气生产。这些研究与新的物理搜索紧密结合在一起，因为它们测量的过程是特定搜索目标的重要背景。这些通道中的任何一个信号的存在都将对我们对粒子物理的理解产生深远的影响，而确定它的不存在将对粒子物理标准模型以外的物理模型提供重要的限制。

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.