Measurement of the angular coefficients in B to D mu nu decays

B 到 D mu nu 衰减中角度系数的测量

• 批准号: 2271046
• 金额: --
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2271046
• 关键词: Measurement; angular; coefficients; mu; nu

Rizwaan Mohammed will have three distinct parts to their work, in addition to full participation in the Oxford graduate course during the first six months of the studentship.The first part of the studentship will be establish, with the support of a departmental electrical design engineer a test bench for a new ultra-fast time discriminator called picoTDC. A prototype chip will be available in early 2020. An older chip call (HPTDC) is available immediately to initialise the test bench and gain some experience using LabView to gather low-level data from the chip. Once the picoTDC is delivered, characterisation studies should be complete before the 1st year viva. Afterward, the student will help construct a fast timing reference system for use in a CERN test beam. A departmental and mechanical engineer will assist this project, producing bespoke electronic boards and mechanics. The student should take intellectual responsibility for understanding the components' function, commissioning of the complete system in Oxford and providing user documentation.The second part will be an angular analysis of the semileptonic decay, B->D*munu using a recently proposed method based on angular variables. This work will use fitting tools that have been developed by the Oxford group for a similar analysis of B->D*taunu decays; the tau mode is studied by another Oxford D.Phil. Both analyses will rely on template fitting built on TensorFlow for fast execution of fitting in multiple dimensions. Both analyses will measure a set of 11 angular coefficients in a model independent manner, as well as a model-dependant overall yield. All parameters are predicted by the Standard Model. The similarly of the analysis implementation will be key to minimising doubts and systematics. This work will use the whole Run 1+Run 2 LHCb datasets (2011-2018). The student will work closely with a post-doc at Oxford as well as a student at Manchester University who is developing the selection of B->D*munu, though not with the Oxford method in mind. The analysis should complete within 2.5 years with 50% effort, targeting the winter conference season of 2022.The third part of the project will bring the student's timing reference system to CERN for operation in a test beam that will operate prototype silicon detectors (called "Timepix4") in 2021 and 2022. These pixel detectors are a stepping-stone to a technological solution for Upgrade II of LHCb. The big-picture purpose of the test beam will be to demonstrate with what precision a "telescope" of 4-8 Timepix4 chips can measure the passage of a particle. At least 50ps is expected with a goal of demonstrating 20ps with respect to the reference time provided by the Oxford system. The student will participate in the test beam activities with around 15 international collaborators. The principal contribution will be the integration of the Oxford system into the telescope data acquisition, and performing the calibration.A long-term attachment (LTA) at CERN is foreseen for the test beams. This would be from July 2021 until September 2022. The student may extend this by three months. Short term travel funds will be split roughly equally between conferences and trips to Geneva in the second year. Two conferences are envisaged, one presenting physics results and the second to an instrumentation conference. The first year report (June 2020) could report on the picoTDC characterisation and design of the fast timing system and the confirmation report (January 2022) will summarise the semileptonic analysis. The final thesis should contain both hardware and physics analysis aspects of the DPhil. with a submission soon after the end of Hilary term 2023.

Rizwaan Mohammed除了在前六个月全面参加牛津大学的研究生课程外，他们的工作将有三个不同的部分。在一名部门电气设计工程师的支持下，该奖学金的第一部分将建立一个名为picoTDC的新型超快时间鉴别器的测试台。原型芯片将于2020年初上市。一个旧的芯片调用（HPTDC）可以立即初始化测试台，并获得一些使用LabView从芯片收集低级数据的经验。一旦交付picoTDC，应在活体第一年之前完成表征研究。之后，该学生将帮助构建一个用于欧洲核子研究中心测试光束的快速定时参考系统。一个部门和机械工程师将协助这个项目，生产定制的电子板和机械。学生应该负责理解组件的功能，在牛津调试完整的系统，并提供用户文档。第二部分将使用最近提出的基于角变量的方法对半光子衰变B->D*munu进行角分析。这项工作将使用牛津小组开发的拟合工具，对B- b> D*taunu衰变进行类似的分析；另一位牛津大学的博士研究了tau模式。这两种分析都将依赖于基于TensorFlow的模板拟合，以便在多个维度上快速执行拟合。这两种分析都将以独立于模型的方式测量一组11个角系数，以及依赖于模型的总产量。所有参数都由标准模型预测。类似的分析实现将是最小化疑虑和系统化的关键。本工作将使用整个Run 1+Run 2 LHCb数据集（2011-2018）。这名学生将与牛津大学的一名博士后以及曼彻斯特大学的一名学生密切合作，后者正在开发B- b> D*munu的选择，但并没有考虑到牛津的方法。以2022年冬季会议为目标，以50%的努力在2.5年内完成分析。该项目的第三部分将把学生的定时参考系统带到欧洲核子研究中心，在2021年和2022年的测试光束中运行原型硅探测器（称为“Timepix4”）。这些像素探测器是LHCb升级II的技术解决方案的踏脚石。测试光束的主要目的是演示4-8个Timepix4芯片组成的“望远镜”能以多高的精度测量粒子的移动。预期至少为50ps，目标是与牛津系统提供的参考时间相比达到20ps。该学生将与大约15个国际合作者一起参加测试光束活动。主要的贡献将是将牛津系统集成到望远镜数据采集中，并进行校准。欧洲核子研究中心（CERN）预计将对测试光束进行长期连接（LTA）。这将从2021年7月到2022年9月。学生可以延长三个月。短期旅行经费将大致平均分配给第二年参加会议和前往日内瓦的旅行。预计将举行两次会议，一次是物理成果会议，另一次是仪器会议。第一年报告（2020年6月）可以报告快速定时系统的皮otdc特征和设计，确认报告（2022年1月）将总结半光子分析。最后的论文应该包含哲学博士的硬件和物理分析方面。在希拉里2023年任期结束后不久提交。