2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/204930In the last few years it has become possible to study low energy pi pi scattering in kaon decays to three pions, thanks to the high statistics measurement of K+- -> pi+- pi0 pi0 decays performed by the NA48/2 experiment at the CERN SPS. At the pi+ pi- threshold, the pi0 pi0 mass spectrum exhibits a Wigner-cusp, from which the S-wave pi pi scattering lengths are extracted with high precision. This measurement is complementary to the extraction of the scattering lengths from K_e4 decays, which is also performed by the NA48/2 experiment.10 pages, proceedings of plenary talk at MENU 2007, FZ Juelich, Sep 2007 (final version after referee's comments)High Energy Physics - Experimenttext