Dirac form factors and electric charge radii of baryons in the combined chiral and 1 /Nc expansions

The baryon Dirac form factor is computed at one-loop order in large-Nc baryon chiral perturbation theory, where Nc is the number of color charges. Loop graphs with octet and decuplet intermediate states are systematically incorporated into the analysis and the effects of the decuplet-octet mass difference are accounted for. There are large-Nc cancellations between different one-loop graphs as a consequence of the large-Nc spin-flavor symmetry of QCD baryons. As a byproduct, the mean-square charge radius is also computed through a detailed numerical analysis. The predictions of large-Nc baryon chiral perturbation theory are in very good agreement both with the expectations from the 1/Nc expansion and with the experimental data. © 2015 American Physical Society.

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