The baryon Dirac form factor is computed at one-loop order in large-$N_c$ baryon chiral perturbation theory, where $N_c$ 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-$N_c$ cancellations between different one-loop graphs as a consequence of the large-$N_c$ 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-$N_c$ baryon chiral perturbation theory are in very good agreement both with the expectations from the $1/N_c$ expansion and with the experimental data.

• Received 14 September 2015

DOI:https://doi.org/10.1103/PhysRevD.92.094026