Hadron electromagnetic mass differences. [Bag model, SU(4) multiplets, up and down quarks, sum rules

Abstract

Mass differences between members of isotopic spin multiplets of hadrons are calculated in the M.I.T. bag model. All low mass, SU(4) multiplets of spin 0, /sup 1///sub 2/, 1, and /sup 3///sub 2/ particles are considered. Both Coulomb and magnetic contributions to mass differences are evaluated without the assumption of SU(6) degenerate intermediate states. The mass difference between the ''up'' and the ''down'' quarks inside the bag is not (necessarily) taken to be a constant: a parameterization is proposed for it that works well for its contribution to known hadron electromagnetic mass differences. Based on the parametrization a class of sum rules is presented for charmed particle electromagnetic mass differences.