Remarks on Electromagnetic Splittings in Charmed Mesons

It has recently been predicted by De Rújula et al. that $m\left(D^{+}\right)-m\left(D^0\right)\sim 15$ MeV. The purpose of this Letter is to criticize this prediction and to examine in detail the mechanism responsible for meson mass splittings. It is concluded that electromagnetic splittings of hadrons cannot reliably be estimated using the present atomic models of hadrons. New terms are probably needed in the electromagnetic part of the potential.