ELECTROMAGNETIC SPLITTINGS AND LIGHT-QUARK MASSES

A method for computing electromagnetic properties of hadrons in lattic e QCD is described. The electromagnetic field is introduced dynamicall y. using a noncompact formulation. Employing enhanced electric charges . the dependence of the pseudoscalar meson mass on the (anti)quark cha rges and masses can be accurately calculated. At beta = 5.7 with Wilso n action, the pi(+) - pi(0) splitting is found to be 4.9(3) MeV. Using the measured K-0 - K+ splitting, we also find m(u)/m(d) = .512(6). Sy stematic errors are discussed. Preliminary results for vector meson sp littings are also presented.