Studies of Basic Symmetries and Fundamental Constants with Muons and Pions

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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.