Studies of Basic Symmetrics and Fundamental Constants with Muons and Pions

1 Project summary We propose research on basic symmetries and fundamental constants with beams of muons and pions. The research involves measurements of quantities closely connected to the underlying symmetries of the standard model, the hypothetical symmetries of a deeper theory, and the realizations of approximate symmetries at low energies. In p,Lan at PSI we will measure the positive muon lifetime 7J1+to ::f:l ppm and determine the Fermi coupling constant GF to similar accuracy, a twenty-fold improvement over earlier experiments. The Fermi constant is a textbook quantity, and is important as a fundamental parameter of the electroweak interaction and for precision testing of the standard model. In p,Cap at PSI we will measure the lifetimes of positive muons and negative muons in H2 ga.,:>to ::f:l0 ppm and thereby deduce the proton's weak coupling gp to ::f:7% accuracy, a five-fold improvement over earlier work in H2 gas. The determination of gp represents an important test of approximate chiral symmetry and its low energy manifestation. In expt. 869 at TRIUMF we will determine the 7r-P -+ 7r°n cross section at low energies and forward angles. These special kinematics will afford a precise test of isospin breaking via the careful comparison of 7rIp elastic scattering and 7r-P -+ 7r°n charge exchange. Recent theoretical work on pion-nucleon interactions at low energies have suggested unexpectedly large isospin breaking, and fueled much debate. We also propose development work on a high-speed data acquisition for a new measurement of the muon magnetic moment using the existing BNL storage ring with upgraded injection, detectors, electronics and acquisition. The recent measurement of the muon anomaly aJ1by the g-2 collaboration shows a 2.4 (J disagreement with the standard model, and makes a compelling case for an improved measurement. The BNL PAC has strongly endorsed our proposal (expt. 969). The PI's group has leadership roles and major responsibilities in these projects. The PI is spokesperson for TRIUMF expt. 869, team leader for data acquisition in p,Lan, and responsible for acquisition prototyping in BNL expt. 969. UK post-doc Dr. V. Tishchenko is our on-site manager for the data acquisition in the p,Lan experiment. UK graduate student Ms. Y. Jia is the dissertation student on expt. 869 and UK graduate student Mr. S. Rath is our dissertation student on p,Lan. The proposed research involves experiments at various stages of development, running and analysis. In p,Lan and p,Cap we are completing the commissioning of the final set-ups for full intensity running and plan for production running in 2006 and 2007. In TRIUMF expt. 869 the data taking is completed and the analysis will be finished by year-end of proposal year one. In BNL expt. 969 our prototyping work is important for the development of a full technical design report and a full funding proposal for the experiment. The PI pursues an integrated approach to research and teaching. The proposal includes continuing efforts to incorporate symmetry topics into the undergraduate physics curriculum and involve physics majors in our research work. In addition, the PI will continue his program that involves computer science students in data acquisition development through MS thesis projects and his efforts to improve the representation of women and minorities in physics through his leadership of the Dept's. graduate recruiting committee. To support the research activities we request funding of $626,685 over three years. These funds will support one post-doc, two graduate students, and equipment, supplies and travel. The Univ. of Kentucky is supporting the research through a reduced off-campus indirect cost rate. 1