Precision Measurement of Electromagnetic Properties of Light Pseudoscalar Mesons via the Primakoff Effect

利用普里马科夫效应精确测量轻赝标量介子的电磁特性

• 批准号: 0245072
• 负责人: Liping Gan
• 金额: --
• 依托单位: University of North Carolina at Wilmington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-05-01 至 2008-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0245072&HistoricalAwards=false
• 关键词: Precision; Measurement; Electromagnetic; Properties; Light

This project is designed to integrate important contributions to the ongoing research at Jefferson lab with an educational experience for promising undergraduate students. A team of undergraduate students and one full time faculty member will carry out this work both at Jefferson Lab and in the University of North Carolina at Wilmington (UNCW) detector development laboratory. The primary goal of this project is to optimize the undergraduate experience while making important contribution to our understanding of low energy QCD by carrying out the high precision measurements of two-photon decay widths and the transition form factors of three neutral light pseudoscalar mesons pion-zero, eta and eta' (eta-prime) via the Primakoff effect. Two basic phenomena in QCD, namely the spontaneous break of chiral symmetry and the chiral anomalies, are manifested in their most unambiguous form in the sector of light pseudoscalar mesons. The anomalies particularly drive the two-photon decays of the pion-zero, eta and eta' and also provide a large fraction of the eta' mass. The UNCW group will work on current development of a high precision measurement of neutral pion lifetime experiment, while the advent of a 12 GeV electron beam at Jefferson Laboratory will make it possible to extend this program to eta and eta'. These measurements would have a significant impact on the current knowledge of the ratios of quark masses, the mixing angle of eta and eta', and provide model independent extractions of the size of the electromagnetic interaction radii of mesons. In addition, more precise knowledge of the transition form factors of the pseudoscalar mesons will allow a better determination of the light-by-light scattering contributions to the anomalous magnetic moment of the muon, which is one of the most sensitive quantities to new physics beyond the Standard Model.The UNCW group will play a leading role in developing a multi-channel scintillating beam profile detector, optimizing the experimental setup for future eta and eta' measurements by Monte Carlo simulation, while continuing to make significant contributions to develop a multi-channel crystal calorimeter and pair-spectrometer projects for the neutral pion lifetime measurement experiment. This research will engage undergraduate science majors as key contributors. The involvement of undergraduates has become one of the trademarks of the UNCW research group and matches the university's commitment to provide a high quality undergraduate learning experience

该项目旨在将杰斐逊实验室正在进行的研究的重要贡献与有前途的本科生的教育经验相结合。一个由本科生和一名全职教师组成的团队将在杰斐逊实验室和北卡罗来纳大学威尔明顿分校（UNCW）探测器开发实验室开展这项工作。本项目的主要目标是通过Primakoff效应对三个中性光伪标量介子的双光子衰变宽度和跃迁形式因子进行高精度测量，优化本科体验，同时为我们对低能QCD的理解做出重要贡献。手性对称性的自发破缺和手性异常这两个QCD的基本现象在光赝标量介子扇形中表现得最为明确。这些异常特别地驱动了介子零、eta和eta‘的双光子衰变，并且也提供了很大一部分eta’质量。UNCW小组将致力于目前中性介子寿命实验的高精度测量，而杰斐逊实验室12 GeV电子束的出现将使该计划扩展到eta和eta'成为可能。这些测量结果将对目前关于夸克质量比、eta和eta'的混合角的知识产生重大影响，并提供与模型无关的介子电磁相互作用半径大小的提取。此外，对伪标量介子的跃迁形式因子的更精确的了解，将使我们能够更好地确定逐光散射对μ子异常磁矩的贡献，这是超越标准模型的新物理学中最敏感的量之一。UNCW小组将在开发多通道闪烁光束剖面探测器，优化未来通过蒙特卡罗模拟测量eta和eta的实验设置方面发挥主导作用，同时继续为开发多通道晶体量热计和中性介子寿命测量实验的成对光谱仪项目做出重要贡献。这项研究将吸引本科理科专业的学生作为主要贡献者。本科生的参与已经成为UNCW研究小组的标志之一，并且符合大学提供高质量本科学习体验的承诺