2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/179094Recent experiments show that the isospin-violating mass splitting of the B mesons is very small, but the best fits with a QCD sum rule analysis give a splitting of at least 1.0 MeV. The isospin-violating mass splittings of the charmed mesons, on the other hand, are in agreement with experiment. In this letter we show that the inclusion of 2$^{nd}$ kind QED penguin diagrams can account for this discrepancy within the errors in the QCD sum rule method.9 pages, latex, 2 figuresHigh Energy Physics - PhenomenologyNuclear Theorytext