\eta and \eta' transition form factors from rational approximants

Understand

The \eta and \eta' transition form factors in the space-like region are analyzed at low and intermediate energies in a model-independent way through the use of rational approximants.

• The slope and curvature parameters of the form factors as well as their values at zero and infinity are extracted from experimental data.
• The impact of these results on the mixing parameters of the \eta-\eta' system and the pseudoscalar-exchange contributions to the hadronic light-by-light scattering part of the anomalous magnetic moment are also discussed.