ISOSPIN SPLITTINGS OF CHARM AND BOTTOM MESONS

The mass splittings of the pseudoscalar and vector D and B light-heavy quark systems are being calculated using the method of QCD sum rules. Electromagnetic, quark mass, and nonperturbative QCD effects are all included. In this progress report we demonstrate that nonperturbative isospin violating effects are small and emphasize the need for an accu rate gauge invariant calculation of electromagnetic effects, which wou ld allow the isospin splittings for heavy-light masons to give valuabl e information about quark mass splittings.