Tests of chiral perturbation theory with $K_{e4}$ decays at NA48/2

The experiment NA48/2 at CERN SPS performed high precision measurement of the form factors of $K^{\pm} \rightarrow \pi^{+}\pi^{-}e^{\pm}\nu$ decays and s-wave $\pi \pi$ scattering lengths $a_{0}$ and $a_{2}$ for isospin 0 and 2, respectively. The preliminary result on the full available statistics of more than 1 million $K^{\pm}_{e4}$ decays achieves a precision similar to the theoretical one and provides excellent test of Chiral Perturbation Theory.