Isospin Breaking in Kaon Decays to Pions

Summary, in English

The five different K -> 3 Pi and the three K -> 2 Pi decays are calculated in Chiral Perturbation Theory. The calculation is done using different approximations, to study whether this changes the result significantly. First the isospin approximation is used. Discrepancies are then found between theory and experiment. Further calculations without the isospin approximation are then done to see if this solves the found problems. The purpose is two-fold. To test the validity of Chiral Perturbation Theory and to fix some of the unknown parameters in the theory.