Reanalysis of pion-pion phase shifts from K→ππ decays

We re-investigate the impact of isospin violation for extracting the s-wave ππ scattering phase shift difference δ0(MK)−δ2(MK) from K→ππ decays. Compared to our previous analysis in 2003, more precise experimental data and improved knowledge of low-energy constants are used. In addition, we employ a more robust data-driven method to obtain the phase shift difference δ0(MK)−δ2(MK)=(52.5±0.8exp±2.8theor)°.