Speaker
Andrea Vacchi
Description
By using the RAL-RIKEN intense pulsed muon beam and an on-purpose developed high-energy mid infrared tunable laser the FAMU experiment will measure the hyperfine splitting in the ground state of muonic hydrogen ΔEhfs(μ-p)1S with a precision δλ/λ < 10-5 providing crucial information on proton structure and muon-nucleon interaction. Specifically FAMU will provide rZ, the Zemach radius of the proton with higher precision, than what was previously possible, disentangling discordant theoretical values and will quantify any level of discrepancy that may exist between values of rZ as extracted from hydrogen and muonic hydrogen. The aim is to sett a cornerstone result about not yet explained anomalies on the charge rch radius of the proton. The Zemach radius rZ and the charge radius rch are the only proton shape-related values that can be directly extracted from experimental data, and rZ is the only one that gives information about the proton's magnetic dipole moment distribution. The results of the preparatory phase and the present status of the experiment will be presented.
