Studies of Basic Symmetries and Fundamental Constants with Muons and Pions

这个项目的重点是测试基本的对称性，并确定标准模型的基本常数。拟议的研究包括瑞士保罗·谢勒研究所的muLan/muCap实验，以及加拿大triumf设施的869号专家。实验将确定电弱相互作用的费米常数精度为百万分之一，质子弱相互作用的诱导伪标量耦合常数精度为6%，并高精度地测试介子-核子相互作用的同位旋对称性。在PSI的mulan实验和muCap实验都涉及到正/负μ子寿命的高精度测量，并利用了新技术，包括强脉冲μ子束、新型探测器、高速电子设备和数据采集。869利用重新配置的RMC谱仪作为pi0谱仪来研究介子和核子之间的基本相互作用。muCap和exte869都将讨论在质子和中子的低能相互作用中实现量子色动力学的两个重要对称性——手性对称性和同位旋对称性。“花木兰”实验中费米常数的确定将为所有的电弱计算确定一个基本参数，并促进标准模型的精确测试。该项目包括几个具有更广泛影响的领域。PI将继续与物理专业学生、计算机科学研究生和物理研究生一起参与实验项目以及高速电子和数据采集的相关开发。PI还将继续在物理和工程专业的课堂上教授对称原理和守恒定律。此外，测量本身是教科书量（例如费米常数和μ子磁矩），并且具有广泛的影响。

This project is focused on the testing of basic symmetries,and determination of fundamental constants, of the standard model.The proposed research involves the muLan/muCap experiments atthe Paul Scherrer Institute, Switzerland, and expt. 869 at theTRIUMF facility, Canada. The experiments will determine the Fermiconstant of the electroweak interaction to part-per-millionaccuracy, the induced pseudoscalar coupling constant of theproton's weak interaction to six percent accuracy, and test isospinsymmetry in pion-nucleon interactions to high precision. Both themuLan experiment and the muCap experiment at PSI involve highprecision measurements of positive/negative muon lifetimes andutilize new technologies including an intense pulsed muon beam,novel detectors, and high-speed electronics and data acquisition.Expt. 869 utilizes a reconfigured RMC spectrometer as a pi0spectrometer for the investigation of the elementary interactionbetween pions and nucleons. Both muCap and expt 869 will addressthe realization of two important symmetries of quantum chromodynamics-- chiral symmetry and isospin symmetry -- in low energy interactionsof protons and neutrons. The determination of the Fermi constantby the muLan experiment will both determine a fundamental parameterfor all electroweak calculations and facilitate the precision testingof the standard model.The project includes several areas for broader impact. The PI willcontinue his involvement of physics majors, computer science graduatestudents and physics graduate students in both the experimental programand the related development of high-speed electronics and dataacquisition. The PI will also continue his efforts in the teaching ofsymmetry principles and conservation laws in classes for physicsand engineering majors. Moreover, the measurements themselves areof textbook quantities (e.g. the Fermi constant and the muon magneticmoment) and have broad impact in their own right.