γ*γ → π0 transition form factor at low energies from a model-independent approach

The recent measured gamma*gamma -> pi(0) transition form factor in the spacelike region by the Belle Collaboration together with the previously published results by CLEO, CELLO, and BABAR collaborations, are analyzed using the mathematical theory of Pade approximants. The theory provides a good and systematic description of the low-energy region exemplified here with the extraction of the slope a(pi) and curvature b(pi) of the form factor in a model-independent way. Their impact on the pion exchange contribution to the hadronic light-by-light scattering part of the anomalous magnetic moment a(mu) is also discussed.