Electromagnetic self energies of pseudoscalar mesons and Dashen\u27s theorem

The calculation of the electromagnetic mass shifts of pi, K mesons is studied using a model incorporating chiral symmetry and vector dominance. Significant SU(3) breaking to Dashen s theorem is found, allowing a resolution of the long-standing discrepancy between the quark-mass ratio (md —m„)/I, found from g-\u3e3pi decay and that from the K+-K0 mass difference