Measuring the muonic H ground state hyperfine splitting with FAMU

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 rZ, the Zemach radius of the proton with higher precision, than what was previously possible, disentangling discordant theoretical values. The aim is to set a cornerstone result about not yet explained anomalies on the charge radius rch 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 status of the experiment is presented.