Experimental Study of Heavy Flavor and CP Violation with the LHCb Experiment at the CERN LHC Collider

在 CERN LHC 对撞机上使用 LHCb 实验进行重味和 CP 破坏的实验研究

• 批准号: 1907466
• 负责人: Abolhassan Jawahery
• 金额: $ 32.5万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1907466&HistoricalAwards=false
• 关键词: Experimental; Study; Heavy; Flavor; CP

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 of 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 at CERN. However, the Standard Model as it currently exists, leaves open many questions about the universe. These include why matter dominates over anti-matter in the Universe (CP violation), the values of the masses of the fundamental constituents, the quarks and the leptons, the size of the mixings among the quarks, and separately among the leptons, and the properties of dark matter. Most explanations require the presence of new particles, symmetries or forces, which we call Beyond the Standard Model Physics (BSM). This project is designed to pursue searches for BSM physics. The LHC is the premier High Energy Physics particle accelerator in the world and is currently operating at the CERN laboratory near Geneva Switzerland, one of the foremost facilities for answering these BSM questions. The Maryland group is a collaboration member of LHCb, an experiment designed specifically to study the decays of hadrons containing b or c quarks at the LHC. The goal of LHCb is to identify new physics in nature by examining the properties of hadrons containing these quarks. New physics, or new forces, can be manifest by particles, as yet to be discovered, whose presence would modify decay rates and CP violating asymmetries of hadrons containing the b and c quarks, and thus allow new phenomena to be observed indirectly. Analytically, the Maryland program is focused on measurements related to two of the current anomalies in the decays of B mesons: hints of departure from Lepton Flavor Universality in semi-leptonic B decays and the long-standing so-called K-pi puzzle where the measured CP asymmetries in the family of B decays into the K-pi final state deviate from the expected simple predictions. These anomalies, if confirmed, could be due to the imprints of BSM physics. Technically, the Maryland group leads the development and construction of the off-detector electronics for the new upstream tracker (UT) in the LHCb upgrade and participation in the installation and commissioning of the tracker. The UT represents a major US contribution to the upgrade of the experiment to improve event reconstruction overall and particularly for rare events of the type under study by the Maryland team.The group works closely with an outreach program run by the physics and astronomy departments at the University of Maryland, called GRAD-MAP, which is aimed at providing research and training opportunities for undergraduates from underrepresented groups in the Maryland and Washington area community colleges. The LHCb experiment, with its technical challenges and exciting physics program, serves as a major attractor for student participation.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.

20 世纪的主要智力成就之一是粒子物理学标准模型 (SM) 的发展。该模型成功地将当时已知的所有基本粒子分类为具有相似量子特性的群的层次结构。迄今为止，欧洲核子研究中心大型强子对撞机希格斯玻色子的发现证实了该模型的有效性。然而，目前存在的标准模型留下了许多关于宇宙的问题。其中包括为什么宇宙中物质比反物质占主导地位（CP破坏）、基本成分、夸克和轻子的质量值、夸克之间以及轻子之间单独混合的大小，以及暗物质的特性。大多数解释都需要新粒子、对称性或力的存在，我们称之为超越标准模型物理（BSM）。该项目旨在探索 BSM 物理学。 LHC 是世界上首屈一指的高能物理粒子加速器，目前在瑞士日内瓦附近的 CERN 实验室运行，该实验室是回答这些 BSM 问题的最重要的设施之一。马里兰小组是 LHCb 的合作成员，LHCb 是一项专门设计用于研究 LHC 中含有 b 或 c 夸克的强子衰变的实验。 LHCb 的目标是通过检查包含这些夸克的强子的性质来识别自然界中的新物理学。新物理或新力量可以通过尚未发现的粒子来体现，它们的存在将改变包含 b 和 c 夸克的强子的衰变率和 CP 破坏不对称性，从而允许间接观察到新现象。从分析上讲，马里兰计划的重点是与当前 B 介子衰变中的两个异常相关的测量：半轻子 B 衰变中偏离轻子风味普遍性的暗示以及长期存在的所谓 K-pi 难题，其中B族中测量的CP不对称性衰减到K-pi最终状态偏离了预期的简单预测。这些异常现象如果得到证实，可能是由于 BSM 物理的印记造成的。从技术上讲，马里兰小组领导 LHCb 升级中新型上游跟踪器 (UT) 的探测器外电子设备的开发和建设，并参与跟踪器的安装和调试。 UT 代表了美国对实验升级的重大贡献，以改善整体事件重建，特别是马里兰团队正在研究的罕见事件类型。该小组与物理和天文学系运行的外展计划密切合作。马里兰大学，名为 GRAD-MAP，旨在为马里兰州和华盛顿地区社区学院中代表性不足群体的本科生提供研究和培训机会。 LHCb 实验以其技术挑战和令人兴奋的物理项目，成为学生参与的主要吸引力。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。