Hadron Electromagnetic Mass Differences and a Prediction ofB+−B0

It is proposed that the dynamical contribution to the hadron electromagnetic mass difference induced by the splitting of the up and down quark masses can be extracted phenomenologically from the quark masses by interpolation, in accordance with general QCD assumptions. The results are consistent with all observed electromagnetic mass differences. The model-independent prediction $B^0-B^{+}=2.3\mathrm{}\pm 0.3$ MeV will serve as a crucial test for these assumptions. A useful mass formula for the $s$-wave hadron ground states is also presented.