Pere Masjuan

The \(\eta \) transition form factor from space- and time-like experimental data

The

Padé approximants and resonance poles

\eta

Overview of the hadronic light-by-light contribution to the muon (g−2)

η transition form factor is analyzed for the first time in both space- and time-like regions at low and intermediate energies in a model-independent approach through the use of rational approximants. The

Pseudoscalar transition form factors: (g − 2) of the muon, pseudoscalar decays into lepton pairs, and the η – η′ mixing

\eta \rightarrow e^+e^-\gamma

η and η′ transition form factors from Padé approximants

η→e+e-γ experimental data provided by the A2 Collaboration in the very low-energy region of the dielectron invariant mass distribution allows for the extraction of the most precise up-to-date slope and curvature parameters of the form factors as well as their values at zero and infinity. The impact of these new results on the mixing parameters of the