On the basis of a next-to-leading-order calculation in chiral perturbation theory, the first complete analysis of isospin breaking for direct CP violation in K-0-->2pi decays is performed. We find a destructive interference between three different sources of isospin violation in the CP violation parameter epsilon('). Within the uncertainties of large-N-c estimates for the low-energy constants, the isospin violating correction for epsilon(') is below 15%.
Cirigliano, Vincenzo Ecker, Gerhard Neufeld, Helmut Pich Zardoya, Antonio 2003 Isospin violation in epsilon' Physical Review Letters 91 16 162001
