Proton charge radius extraction from electron scattering data using dispersively improved chiral effective field theory

In electron scattering, the proton radius is determined by determining the slope of the charge form factor at a Q² of zero. Typically this requires extrapolating fits of the experimental data and will give different radii depending on the function used. I will present a radius extraction using a novel theoretical framework based on analyticity and first-principles dynamical input from chiral EFT (dispersively improved chiral EFT, DIchEFT). The spacelike form factor data are compared with the DIchEFT predictions for various fixed radii, and the physical radius is determined by the best match between theory and experiment up to Q² ~ 0.5 GeV². We obtain a radius of 0.844(7) fm, in agreement with the high-precision muonic hydrogen results.