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

2019; American Physical Society; Volume: 99; Issue: 4 Linguagem: Inglês

10.1103/physrevc.99.044303

2470-0002

J. M. Alarcón, D. W. Higinbotham, Christian Weiß, Z. Ye,

Advanced Chemical Physics Studies

We extract the proton charge radius from the elastic form factor (FF) data using a novel theoretical framework combining chiral effective field theory and dispersion analysis. Complex analyticity in the momentum transfer correlates the behavior of the spacelike FF at finite ${Q}^{2}$ with the derivative at ${Q}^{2}=0$. The FF calculated in the predictive theory contains the radius as a free parameter. We determine its value by comparing the predictions with a descriptive global fit of the spacelike FF data, taking into account the theoretical and experimental uncertainties. Our method allows us to use the finite-${Q}^{2}$ FF data for constraining the radius (up to ${Q}^{2}\ensuremath{\approx}0.5 {\mathrm{GeV}}^{2}$ and larger) and avoids the difficulties arising in methods relying on the ${Q}^{2}\ensuremath{\rightarrow}0$ extrapolation. We obtain a radius of 0.844(7) fm, consistent with the high-precision muonic hydrogen results.