Mr Tomas Husek (Charles University (CZ))
In this talk we will discuss two important processes of the low energy hadron physics: the Dalitz decay of $\pi^0$ and $\pi^0\to e^+e^-$. We briefly summarize experimental and theoretical results on the rare decay $\pi^0\to e^+e^-$. The analytical two-loop QED corrections together with the bremsstrahlung contribution beyond the soft-photon approximation are reviewed. Using the leading logarithm approximation, the possible contribution of QCD corrections is estimated. The complete result is then used to fit the value of the contact interaction coupling to the recent KTeV experiment. This, together with a study of the Dalitz decay $\pi^0\to e^+e^-\gamma$, can be used in the theoretical calculation of the hadronic light-by-light scattering contribution in the $g-2$ type experiments.