Status of the MUSE experiment

The 5.6q difference in proton radii measured with мp atoms and with ep atoms and scattering remains an unexplained puzzle. MUSE will measure the мp and ep elastic scatterings in the same experiment at the same time. The experiment determines cross-sections, two-photon effects, form-factors, and radii and allows мp and ep to be compared with reduced systematic uncertainties. These data should provide the best test of the lepton universality in a scattering experiment to date, about an order of magnitude improvement over previous tests, a 7q radius determination, and improved two-photon measurements.