ππ Scattering Length Measurements from Ke4 and K± →π±π0π0 Decays at NA48/2

We report here the preliminary results on the ππ scattering lengths a 0 and a 2 at NA48/2. We determine a 0 and a 2 by studying two different kaon decay modes. In the K ± → π+ π− e ± v decays (K e4) we measure the form factors of the hadronic current (F, G, H) and the ππ phase difference (δ = δ s — δ p ) in ten independent bins of the π mass spectrum to investigate their variation. Taking into account the isospin simmetry breaking effects and using numerical solutions of the Roy equations we obtain a 0 and a 2. In the K ± → π± π0 π0 events we determine the a 0–a 2 difference and a 2 from a fit to the π0π0 invariant mass distribution (M 00) around M oo=2m π +.