The electromagnetic radii of the proton, neutron and deuteron from spectroscopy of muonic hydrogen and deuterium with the help of chiral EFTs*

The proton "charge radius puzzle" is known to affect the deuteron, so it is really a Z=1 puzzle. I will present the results of our recent calculations of the nuclear polarizability effect in muonic hydrogen (muH) and deuterium (muD) [1-4], and discuss their impact on the extraction of the charge radii of proton, neutron and deuteron. Our latest chiral EFT calculation of the polarizability effect in the hyperfine splitting (hfs) of muonic hydrogen is in condradiction with previous data-driven evaluations based on empirical spin structure functions g1 and g2 of the proton. This has an improtant implication for the first planned measurements of the ground-state hfs transition in muH by the FAMU and CREMA Collaborations.

I will highlight the prospects for improving the data-driven evaluations using the new data from the Jefferson Lab g2p experiment.