The size of the proton: Closing in on the radius puzzle
Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, D-53115, Bonn, Germany
2 Institute for Advanced Simulation and Jülich Center for Hadron Physics, Institut für Kernphysik, Forschungszentrum Jülich, D-52425, Jülich, Germany
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Accepted: 23 October 2012
Published online: 6 November 2012
We analyze the recent electron-proton scattering data from Mainz using a dispersive framework that respects the constraints from analyticity and unitarity on the nucleon structure. We also perform a continued fraction analysis of these data. We find a small electric proton charge radius, r E p = 0.84 −0.01 +0.01 fm, consistent with the recent determination from muonic hydrogen measurements and earlier dispersive analyses. We also extract the proton magnetic radius, r M p = 0.86 −0.03 +0.02 fm, consistent with earlier determinations based on dispersion relations.
© SIF, Springer-Verlag Berlin Heidelberg, 2012