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

ABSTRACT

We extract the proton charge radius from the elastic form factor data using a theoretical framework combining chiral effective field theory and dispersion analysis. Complex analyticity in the momentum transfer correlates the behavior of the spacelike form factor in different $Q^2$ regions and permits the use of data up to $Q^2 \sim$ 0.5 GeV$^2$ in constraining the radius. The predictive theory describes the data with the same accuracy as current descriptive models (global fits). We obtain a radius of 0.844(7) fm, consistent with the high-precision muonic hydrogen results.