On the possibility to measure the π ⁰→γγ decay width and the γ ^∗ γ→π ⁰ transition form factor with the KLOE-2 experiment

Abstract

A possibility of KLOE-2 experiment to measure the width $\varGamma_{\pi^{0} \to\gamma\gamma}$ and the π ⁰ γγ ^∗ form factor F(Q ²) at low invariant masses of the virtual photon in the space-like region is considered. This measurement is an important test of the strong interaction dynamics at low energies. The feasibility is estimated on the basis of a Monte-Carlo simulation. The expected accuracy for $\varGamma_{\pi^{0} \to\gamma\gamma}$ is at a per cent level, which is better than the current experimental world average and theory. The form factor will be measured for the first time at Q ²≤0.1 GeV² in the space-like region. The impact of these measurements on the accuracy of the pion-exchange contribution to the hadronic light-by-light scattering part of the anomalous magnetic moment of the muon is also discussed.