Experimental Particle Physics Research at High Energies

东北大学高能实验粒子物理研究粒子碰撞的高能前沿为发现新粒子和获得粒子如何在最小距离尺度上相互作用的新理解提供了最好的机会之一。粒子物理学的标准模型为这些相互作用提供了理论预测，但众所周知，这个模型是不完整的，需要实验来发现这些预测之外的东西。欧洲核子研究中心实验室的大型强子对撞机（LHC）拥有世界上最高能量的人造粒子碰撞。大型强子对撞机的紧凑型介子螺线管（CMS）实验是一个功能强大的多用途粒子探测器，它的作用就像一个复杂的照相机，旨在观察和记录这种碰撞中发生的事情。本项目支持东北大学三名教师和几名博士后研究员及学生利用CMS实验进行粒子物理实验研究。利用已经记录的数据和正在记录的新数据的综合能力，他们使用现代统计和机器学习技术，将理论预测与根据他们的专业知识量身定制的领域的观测数据进行比较：标准模型物理学，希格斯研究，以及寻找超越标准模型的物理学。从这些研究中获得的知识将完善粒子理论的预测，并进一步探索在最小距离尺度上理解我们的宇宙。该项目还包括在LHC运行3期间运行CMS探测器，以及开发探测器升级，这将推进用于粒子探测的复杂仪器，并具有更广泛的应用。这些升级将使CMS能够利用未来大型强子对撞机（HL-LHC）的高亮度运行，并确保这些仪器可供后代科学家使用。在拟议工作的三年时间里，将完成对Run 2中CMS的完整数据集的分析，并将开发几个分析项目，这些项目将针对或包括Run 3中积累的数据。东北大学CMS小组将继续进行一些有针对性的搜索，以寻找由最近的异常现象或引人注目的理论问题所激发的新物理学：轻夸克搜索，可以解决在测量μ子的g-2时观察到的异常；在多个衰变通道中产生成对的希格斯玻色子，这可能标志着新的物理学正在产生或耦合，并最终将深入了解希格斯势的形式。与此同时，该小组将使用众所周知的Run 2 CMS数据来提高希格斯玻色子标准模型生产的精度和测量范围，以及W+射流和ZZ对。这些测量结果对于精确预测HL-LHC搜索的背景过程非常重要。该小组为CMS实验提供了关键支持，以继续高效运行μ子探测和触发，以及电磁量热系统，将有助于为整个CMS合作提供更广泛的粒子物理研究项目所使用的数据。在HL- LHC的准备工作中，该小组的工作将通过升级μ子系统、μ子触发器和电磁量热计的电子设备来实现在高速率环境中提取物理的新功能，以适应更高的数据速率，并通过实现新的定时探测器来消除大量多重相互作用顶点的歧异。东北大学CMS小组还将通过努力提高多样性、包容性和指导，以及通过与更广泛的科学界和公众的接触和接触，寻求更广泛的影响。该小组将提供特殊的互动机会，邀请来自世界各地的物理学家参加2024年在东北大学校园举办的LHCP会议。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Experimental Particle Physics Research at High Energies Northeastern UniversityThe high energy frontier of particle collisions provides one of the best opportunities to discover new particles and gain new understanding of how particles interact at the smallest distance scale. The standard model of particle physics provides theoretical predictions for these interactions, but this model is known to be incomplete, and experiments are needed to find what lies beyond those predictions. The Large Hadron Collider (LHC) at the CERN laboratory houses the world’s highest energy human-made particle collisions. The Compact Muon Solenoid (CMS) experiment at the LHC is a powerful multipurpose particle detector that acts like a complex camera, which aims to observe and record what happens in such collisions. This project supports the work of three faculty members at Northeastern University plus several postdoctoral researchers and students to conduct experimental particle physics research with the CMS experiment. With the combined power of data already recorded and new data being recorded, they use modern statistical and machine-learning techniques to compare theoretical predictions with the observed data in areas tailored to their expertise: standard model physics, Higgs studies, and search for physics beyond the standard model. The knowledge gained from these studies will refine the predictions of particle theory and further the quest for understanding our universe at the smallest distance scales. The project also includes operation of the CMS detector during LHC Run 3, as well as development of detector upgrades that will advance the sophisticated instrumentation that is used in particle detection and has broader applications. These upgrades will enable CMS to exploit future high luminosity running of the LHC (HL-LHC) and ensure that the instruments are available to future generations of scientists.In the three years spanned in the proposed work, the analysis of the full data set from CMS from Run 2 will reach completion, and several analysis projects will develop that will target or include the data accumulated in Run 3. The Northeastern University CMS group will pursue some targeted searches for new physics motivated by recent anomalies or compelling theoretical questions: Leptoquark searches, which could address anomalies observed in the measurement of g-2 of the muon; the production of pairs of Higgs bosons in multiple decay channels, which can signal new physics in production or couplings, and will ultimately give insight into the form of the Higgs potential. At the same time, the group will use the well-understood Run 2 CMS data to increase the precision and scope of measurements of standard model production of the Higgs boson, as well as W+jets and ZZ pairs. The results of these measurements will be very important for making precise predictions of background processes for searches at the HL-LHC. Critical support provided by the group to the CMS experiment to continue the high-efficiency operation of the muon detection and triggering, and of the electromagnetic calorimetry systems will help to provide data used by the entire CMS collaboration for an even broader program of particle physics investigations. In the preparation for the HL- LHC, the work of the group will implement new capabilities for extracting physics in the high-rate environment through upgrades to the electronics of the muon system, muon trigger, and electromagnetic calorimeter to accommodate a much higher rate of data, and through the realization of a new timing detector to disambiguate the large number of multiple interaction vertices. The Northeastern University CMS group will also pursue broader impact through efforts to improve diversity, inclusion, and mentoring, and through outreach and engagement to the wider scientific community and general public. The group will provide special opportunities for interactions by bringing physicists from around the world to the LHCP Conference hosted at the Northeastern University campus in 2024.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.