The Flavour Anomalies: Fluke, Fallacy or New Physics?

风味异常：侥幸、谬论还是新物理学？

• 批准号: 2310073
• 负责人: Eluned Smith
• 金额: $ 54万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2310073&HistoricalAwards=false
• 关键词: Flavour; Anomalies; Fluke; Fallacy; New

The Standard Model of particle physics represents our best current knowledge of the fundamental particles that make up our universe and the interactions (forces) that govern them. Although to date most fundamental particles have been observed to behave as predicted by the Standard Model, cosmological observations tell us that the Standard Model cannot be the complete picture. For example, in the Standard Model, matter and anti-matter are a near-perfect mirror of each other. However, the dominance of matter in our universe tells us that there must be some, as of yet unknown, interaction breaking this matter, anti-matter symmetry. The LHCb experiment is one of the four experiments situated on the Large Hadron Collider (LHC) at CERN. It is designed to make precision measurements of a particle called a beauty (b) quark. This award focuses on the study of b-quark decays which are very suppressed in the Standard Model. By precisely measuring the rates at which these rare processes happen, we can infer the existence of new interactions, not described within the Standard Model. Over recent years, measurements of these rare b decays have shown deviations with Standard Model predictions. This award will further our understanding behind what is causing these anomalies, with the goal of determining whether their origin could be the first sign of a beyond-the-Standard-Model process at the LHC. The PI of this project is the founder of the Laura Bassi initiative within the LHCb collaboration, which brings together early career researchers interested in tackling issues of gender and diversity within particle physics. This grant will support the PI’s continued work in this area.Whereas the tensions observed in rare b-decays can be over 5 standard deviations with respect to the Standard Model, these deviations could be due to poor theoretical descriptions of non-local hadronic effects, which cannot be derived from first principles in the Standard Model. This award performs a novel data-driven measurement of non-local hadronic effects in the decay B^0→K^(*0) μ+μ-, providing a crucial part of the flavour-anomaly puzzle. Similar methods are used to measure non-local tauonic contributions to B^0→K^(*0) μ^+ μ^-, via the decay B^0→K^(*0) [τ^+ τ^-→μ^+μ- ]. The expected sensitivity on B(B^0→K^(*0) τ^+ τ^- ) obtained using this method is world-leading. Measurements of b→sτ^+ τ^- are critical to understanding the anomalies, as favored new physics explanations predict large enhancements in theses modes. This project will also perform the first fit for the imaginary contributions to the underlying effective couplings in B^0→K^(*0) μ+μ- , with the proposed method resulting in an order-of-magnitude improvement on CP-violation constraints in b→sl+l- decays. This measurement is interesting in light of the flavor anomalies, and because constraints on beyond-the-SM CP violation are central to understanding the dominance of matter over anti-matter in the universe. This project will also commission and validate the performance of the LHCb Upgrade I detector, which takes data during the LHC Run 3 (2022-2026) for the first time. This commissioning work will be the cornerstone of subsequent measurements of b→sμ^+ μ^-processes using Run 3 data, which are also performed as part of this project.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.

粒子物理学的标准模型代表了我们对构成宇宙的基本粒子以及控制它们的相互作用（力）的最好的了解，尽管迄今为止大多数基本粒子已被观察到如标准模型所预测的那样，但宇宙学观测结果。告诉我们标准模型不可能是完整的图景，例如，在标准模型中，物质和反物质是彼此近乎完美的镜子，但是，物质在我们的宇宙中的主导地位告诉我们，一定存在。一些目前尚不清楚的相互作用打破了这个问题， LHCb 实验是位于 CERN 大型强子对撞机 (LHC) 上的四个实验之一，旨在对称为美夸克的粒子进行精确测量。通过精确测量这些罕见过程发生的速率，我们可以推断出标准模型中未描述的新相互作用的存在。 b 衰变有该奖项将帮助我们了解导致这些异常的原因，目的是确定它们的起源是否可能是进一步的大型强子对撞机中超出标准模型过程的第一个迹象。该项目是 LHCb 合作中 Laura Bassi 计划的创始人，该计划汇集了对突破粒子物理学中的性别和多样性问题感兴趣的早期职业研究人员。这笔赠款将支持 PI 在该领域的持续工作。稀有的相对于标准模型，b 衰变可能超过 5 个标准偏差，这些偏差可能是由于对非局部强子效应的理论描述不佳，无法从标准模型中的第一原理推导出来。该奖项执行了新颖的数据。衰变 B^0→K^(*0) μ+μ- 中非局域强子效应的驱动测量，提供了风味异常难题的关键部分，类似的方法用于测量非局域 tauonic 贡献。 B^0→K^(*0) μ^+ μ^-，通过衰减 B^0→K^(*0) [τ^+ τ^-→μ^+μ- ] 得到 B 的预期灵敏度。使用这种方法获得的 (B^0→K^(*0) τ^+ τ^- ) 是世界领先的，正如受欢迎的新物理解释所预测的那样，b→sτ^+ τ^- 的测量对于理解异常至关重要。这些模式的大幅增强。项目还将对 B^0→K^(*0) μ+μ- 中潜在有效耦合的虚数贡献进行首次拟合，所提出的方法将导致 CP 违反约束的数量级改进考虑到味道异常，这种测量很有趣，并且因为对超越 SM CP 破坏的限制对于理解宇宙中物质相对反物质的主导地位至关重要。还委托和验证 LHCb Upgrade I 探测器的性能，该探测器首次在 LHC Run 3（2022-2026）期间获取数据。这项调试工作将成为后续使用 Run 测量 b→sμ^+ μ^-过程的基石。 3 数据，这些数据也是该项目的一部分。该奖项反映了 NSF 的法定使命，并且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。