Precision Physics with Muons: Unveiling Physics at the PPM Level
Precision physics with muons spans a long history and is currently an active field worldwide with new results at the Part-per-Million level. It allows for establishing basic parameters of the electroweak theory, exploring fundamental symmetries of low-energy QCD, and testing predictions for new physics beyond the Standard Model. I will discuss the muon capture experiment MuCap at the Paul Scherrer Institute in Switzerland and a future effort at Fermilab as examples of the diverse physics that can be explored with muons. MuCap is determining the pseudo-scalar form factor of the nucleon and has just revealed its final result at unprecedented precision.
The prediction from chiral perturbation theory follows from the concepts of explicit and spontaneous symmetry breaking and comparison with the experimental resullt allows for an important test of the underlying symmetries of QCD. The recently approved new g-2 measurement of the muon anomalous magnetic moment at Fermilab will sensitively test new physics predictions at the low energy frontier, which are complementary to direct searches at high energies.
I will describe the motivation to improve the precision in g-2 by a factor of 4 compared to the last Brookhaven E821 measurement. I will then review the current status of the design of new components and upgrades that are required to achieve the challenging precision goal of 0.14 ppm.