Determination of the S - wave ππ scattering lengths from a study of K ± → π ± π 0 π 0 decays
نویسندگان
چکیده
We report the results from a study of the full sample of ∼ 6.031 × 10 K → πππ decays recorded by the NA48/2 experiment at the CERN SPS. As first observed in this experiment, the ππ invariant mass (M00) distribution shows a cusp-like anomaly in the region around M00 = 2m+, where m+ is the charged pion mass. This anomaly has been interpreted as an effect due mainly to the final state charge exchange scattering process ππ → ππ in K → πππ decay. Fits to the M00 distribution using two different theoretical formulations provide the presently most precise determination of a0 − a2, the difference between the ππ S-wave scattering lengths in the isospin I = 0 and I = 2 states. Higher-order ππ rescattering terms, included in the two formulations, allow also an independent, though less precise, determination of a2. PACS. 13.25.Es Decays of K mesons – 13.75.Lb Meson-meson interactions – 13.40.Ks Electromagnetic corrections to strongand weak-interaction processes – 14.40.Aq π, K and η mesons 2 J.R. Batley et al.: Determination of the S-wave ππ scattering lengths from a study of K → πππ decays
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