Session D7 - Hadron Physics.
ORAL session, Saturday afternoon, May 01
Governor's Square 16, Adam's Mark Hotel
We present a study of isospin breaking in QCD within the consistent framework of Chiral Perturbation Theory including the effects induced by considering the presence of virtual photons on the effective theory. First, the results for the pion decay constants are reviewed. Second, we present the electromagnetic and strong isospin breaking contributions to the baryon masses and the \sigma-terms to fourth order in Lorentz covariant baryon chiral perturbation theory where both Lorentz invariance and chiral power counting are preserved using the infrared regularization prescription for evaluating loop integrals. Finally, we compare our results to those obtained earlier within the heavy baryon formalism of the effective field theory.