Electromagnetic Corrections to the One-Pion-Exchange Potential

Leading-order electromagnetic loop corrections to the one-pion-exchange potential are computed within the framework of chiral perturbation theory. These corrections generate an effective nucleon-nucleon potential, V_πγ, which supplements the sum of one-pion-exchange potential and the nucleon-nucleon Coulomb potential. This potential is charge dependent and its construction is demonstrated to be gauge invariant. The potential V_πγ has been included in the Nijmegen partial-wave analysis of np data. A particular renormalization scheme is chosen that leads to a negligible change in the π^±NN coupling constant and in the np ¹S₀ scattering length and effective range.