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

Rizwaan Mohammed除了在前六个月全面参加牛津大学的研究生课程外，还将有三个不同的工作部分。学生的第一部分将在部门电气设计工程师的支持下建立一个新的超快时间鉴别器PicoTDC的测试台。原型芯片将于2020年初上市。一个较旧的芯片调用(HPTDC)可立即用于初始化测试台，并获得一些使用LabVIEW从芯片收集低级数据的经验。一旦PicoTDC交付，特征研究应在第一年VIVA之前完成。然后，学生将帮助构建用于CERN测试束的快速定时参考系统。一名部门和机械工程师将协助这一项目，生产定制的电子板和机械师。学生应该承担起理解部件功能、牛津大学整个系统的调试和提供用户文档的智力责任。第二部分将使用最近提出的基于角度变量的方法对半轻子衰变B&>D*munu进行角度分析。这项工作将使用牛津小组开发的拟合工具对B-&GT；D*taunu衰变进行类似的分析；另一位牛津D.Phil研究了tau模式。这两种分析都将依赖于基于TensorFlow构建的模板拟合，以快速执行多维拟合。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收益率。所有参数都由标准模型进行预测。类似的分析实施将是最大限度地减少疑虑和系统性的关键。这项工作将使用整个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&gt；D*munu的选择，尽管他们考虑的不是牛津方法。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，以便在2021年和2022年操作原型硅探测器的测试束中进行操作。这些像素探测器是LHCb升级II技术解决方案的垫脚石。测试光束的主要目的将是展示一个由4-8个Timepex4芯片组成的“望远镜”可以以多高的精度测量粒子的通过。预计至少50ps，目标是相对于牛津系统提供的参考时间演示20ps。该学生将与大约15名国际合作者一起参加测试束活动。主要的贡献将是将牛津系统整合到望远镜数据采集中，并进行校准。预计将在欧洲核子研究中心对测试束进行长期连接(LTA)。这将从2021年7月到2022年9月。学生可以将期限延长三个月。短期旅费将大致平均分配给第二年的会议和前往日内瓦的旅行。预计将举行两次会议，一次介绍物理学成果，另一次介绍仪器会议。第一年报告(2020年6月)可以报告微微贸发局的特征和快速计时系统的设计，确认报告(2022年1月)将总结半轻量级分析。最后的论文应该包含DPhil的硬件和物理分析两个方面。在2023年希拉里任期结束后不久提交。

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.