Determination of the ππ scattering lenghts from K^± -->π^±π⁰π⁰ decays

<!--HTML-->The NA48/2 experiment at the CERN SPS has collected more than 100 million fully reconstructed K^±-->π±π⁰π⁰ decays.<br><br> The preliminary analysis of a third of the data shows a sudden change of slope of the π⁰π⁰ invariant mass distribution in the region around 2m, where m is the mass of the charged pion. This anomaly, which was never observed before, is interpreted as a cusp-like effect resulting mainly from the contribution of the K^±-->π±π⁰π⁰ decay amplitude through π⁺π^- -->π⁰π⁰ charge exchange.<br><br> The study of this phenomenon is a new and potentially more accurate method to measure a⁰-a², the difference of the I = 0 and I = 2 S-wave scattering lengths.<br><br> <br><br> The colloquium will consist of two parts: the experiment, given by Italo Mannelli, and the theory by Nicola Cabibbo.<br><br> <BR><BR><I>Organiser(s): Luis Alvarez-Gaume / PH-TH</i><BR><BR><I>Note: * Tea & coffee will be served at 16.00 hrs.</i>