Precision Measurement of ππ Scattering Lengths in K e 4 Decays by NA 48 / 2

Results from NA 48 / 2 on ππ scattering lengths measurements in K ± → π + π − e ± ν and K ± → π 0 π 0 π ± decays

Wigner-cusp in Kaon Decays and Determination of Ππ Scattering Lengths

In the last few years it has become possible to study low energy ππ scattering in kaon decays to three pions, thanks to the high statistics measurement of K → πππ decays performed by the NA48/2 experiment at the CERN SPS. At the ππ threshold, the ππ mass spectrum exhibits a Wigner-cusp, from which the S-wave ππ scattering lengths are extracted with high precision. This measurement is complement...

Spectrum and Decays of Hadronic Atoms

Hadronic atoms are highly non-relativistic loosely bound systems of hadrons mainly formed by the Coulomb interaction. The study of these hadronic bound states has seen growing interest during recent years, because they provide important information on the behavior of QCD at low-energy. The DIRAC collaboration 1 at CERN measures the lifetime of the ππ atom, and plans to determine the ππ scatteri...

ar X iv : h ep - p h / 06 04 08 4 v 1 1 0 A pr 2 00 6 HISKP - TH - 06 / 09 Cusps in K → 3 π decays

The pion mass difference generates a pronounced cusp in K → 3π decays. As has recently been pointed out by Cabibbo and Isidori, an accurate measurement of the cusp may allow one to pin down the S-wave ππ scattering lengths to high precision. Here, we present and illustrate an effective field theory framework that allows one to determine the structure of this cusp in a straightforward manner. Th...

Determination of the S - wave ππ scattering lengths from a study of K ± → π ± π 0 π 0 decays

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 excha...