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: 2309144
• 负责人: Abolhassan Jawahery
• 金额: $ 135万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2309144&HistoricalAwards=false
• 关键词: Experimental; Study; Heavy; Flavor; CP

One of the greatest scientific achievements of the past century has been the development of the Standard Model of elementary particles, the quarks and leptons, and their interactions. The precise tests of the fundamental elements of the Standard Model are among the most important goals of the continuing research in elementary particle physics. This project focuses on an experimental study of heavy flavor, which refers to the studies of the particles containing the charm (c) and the bottom (b) quarks, and CP violation, the differences in the properties of the particles and their antiparticles counterpart. The studies, which will be conducted with the LHCb experiment at the Large Hadron Collider at CERN, include precise tests of the mechanism responsible for the differences in the properties of matter and antimatter as well as examination of the universal behavior of charged leptons, a cornerstone of the Standard Model. The findings of the flavor physics, in particular a potential discovery of new sources of CP violation beyond the Standard Model, will also likely have a profound impact on the understanding of the origin of the matter-antimatter asymmetry in the universe and the field of cosmology. Experimental particle physics also serves as an extremely rich environment for training students at all levels, as well as postdoctoral researchers and engineers at the leading edge of a diverse range of technologies. The Maryland group has had strong record in this area, enabled by the development of the first upgrade of the LHCb detector, and aims to continue and strengthen this program with the next major improvement plan of the detector in the coming decade.The proposed program includes the completion of the commissioning of the upstream tracker in the LHCb upgrade, whose construction has been a key focus of the group, as well as a major participation in the physics analysis of the data recorded by LHCb in Runs 1 & 2 and the anticipated data from the operation of the experiment in the next three years, Run 3. The physics studies program is focused on measurements related to two of the current anomalies in the decays of B mesons: (1) hints of departure from Lepton Flavor Universality in semileptonic B decays and (2) studies of CP violation in the family of B → Kπ decays, where the current measurements of the CP asymmetries deviate from the expected pattern based on isospin symmetry- the long standing so-called ”Kπ” puzzle. These anomalies, if confirmed, could be due to the presence of new physics effects in flavor processes. The program also includes major participation in the development of the next major upgrade of the LHCb detector- Upgrade II, which is expected to lead to significant improvement in the precision of flavor processes. At the current level of precision, measurements of the key flavor observables, currently largely consistent with the Standard Model predictions, impose severe constraints on the energy scale and the structure of new physics models. However, areas of deviations from the SM are emerging, such as signs of lepton non-universality in semileptonic B decays, which are highly sensitive to the presence of new scalars. The precision of future measurements in some key areas, based on the data from LHCb and its upgraded detector, are expected to reach the required sensitivity to clarify some of these anomalies or further strengthen the deviations from the SM predictions. These results could, in conjunction with studies at the energy frontier, point the way to the structure of the physics beyond the SM.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.

上个世纪最伟大的科学成就之一，就是发展了基本粒子、夸克和轻子及其相互作用的标准模型。对标准模型基本元素的精确检验是基本粒子物理学持续研究的最重要目标之一。本项目的重点是重味的实验研究，即研究含有粲夸克（c）和底夸克（B）的粒子，CP破坏，粒子及其反粒子性质的差异。这些研究将在欧洲核子研究中心的大型强子对撞机上进行LHCb实验，包括对物质和反物质性质差异的机制进行精确测试，以及检查带电轻子的普遍行为，这是标准模型的基石。味物理学的发现，特别是在标准模型之外发现CP破坏的新来源，也可能对理解宇宙中物质-反物质不对称性的起源和宇宙学领域产生深远的影响。实验粒子物理学还为培养各级学生以及处于各种技术前沿的博士后研究人员和工程师提供了极其丰富的环境。马里兰州团队在这一领域有着良好的记录，这得益于LHCb探测器的首次升级，并旨在通过未来十年探测器的下一个重大改进计划继续和加强这一计划。拟议的计划包括完成LHCb升级中上游跟踪器的调试，其建设一直是该团队的重点，以及主要参与LHCb在2012年记录的数据的物理分析&，以及未来三年实验运行的预期数据，运行3。物理学研究计划的重点是与B介子衰变中的两个电流异常相关的测量：（1）半轻子B衰变中偏离轻子味普适性的暗示和（2）B → Kπ衰变家族中CP破坏的研究，其中CP不对称性的电流测量偏离了基于同位旋对称性的预期模式-长期存在的所谓“Kπ”难题。这些异常现象，如果得到证实，可能是由于在风味过程中存在新的物理效应。该计划还包括主要参与LHCb检测器的下一个重大升级-升级II的开发，预计将导致调味过程精度的显着提高。在目前的精度水平下，对关键味道观测值的测量，目前在很大程度上与标准模型的预测一致，对新物理模型的能量尺度和结构施加了严格的限制。然而，偏离SM的领域正在出现，例如半轻子B衰变中轻子非普适性的迹象，这对新标量的存在非常敏感。根据LHCb及其升级后的探测器的数据，未来在一些关键领域的测量精度预计将达到所需的灵敏度，以澄清其中一些异常或进一步加强与SM预测的偏差。这些结果可以与能源前沿的研究相结合，为超越SM的物理结构指明方向。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。