Abstrakt
We briefly summarize experimental and theoretical results on the rare decay pi(0) -> e (+) e(-). The notorious 3.3 sigma discrepancy between the Standard Model prediction and the experimental value provided by KTeV collaboration is discussed in the view of a complete set of next- to- leading- order QED radiative corrections.
We also present the Two- Hadron Saturation (THS) scenario for the PVV correlator and apply it to the decay under discussion. The discrepancy under discussion then reduces down to 1.8 sigma.
Finally, we turn our attention the the Dalitz decay pi(0) -> e (+) e(-). We have recalculated the Mikaelian and Smith radiative corrections beyond the soft- photon approximation, i.e. over the whole range of the Dalitz plot and with no restrictions on the radiative photon.
In contrast to the previous calculations, we also included the one- photon irreducible contribution at one- loop level. Our results can be also used for a further treatment of the processes with heavier particles in the final state.