ELECTROMAGNETIC CORRECTIONS FOR PIONS AND KAONS - MASSES AND POLARIZABILITIES

The unknown constants in Chiral Perturbation Theory needed for an all orders analysis of the polarizabilities and electromagnetic correction s to the masses of the pseudo-Goldstone bosons are estimated at leadin g order in 1/N-c. We organize the calculation in an 1/N-c expansion an d separate long- and short-distance physics contributions by introduci ng a Euclidean cut-off: The long-distance part is evaluated using the ENJL model and the short-distance part using perturbative QCD and fact orization. We obtain very good matching between both. We then include these estimates in a full chiral perturbation theory calculation to or der e(2)p(2) for the masses and p(6) for the polarizabilities. For the electromagnetic corrections to the masses, we confirm a large violati on of Dashen's theorem getting a more precise value for this violation . We make a comparison with earlier related work, Some phenomenologica l consequences are discussed too. (C) 1997 Elsevier Science B.V.