The Physics Program of MUSE

The MUon Scattering Experiment (MUSE) at the Paul Scherrer Institute (PSI) seeks primarily to address the proton radius puzzle via investigation of the proton charge radius by performing simultaneous high-precision measurements of elastic electron-proton and muon-proton scattering. Measurements of the proton charge radius will be obtained from a beam of both positively and negatively charged particles from a mixture of electrons, muons, and pions. The experiment runs at varying momenta of 115, 160, and 210 MeV/c. The unique setup of muse allows for a direct muon/electron scattering comparison, a low-Q² region for sensitivity to the proton charge radius (with Q² = 0.002 to 0.082 GeV² /c² ), and for the study of possible two-photon exchange mechanisms.