A revision of radiative corrections to double-Dalitz decays

The radiative corrections to double-Dalitz ($P\to \bar{\mathrm{\ell }}\mathrm{\ell }\overline{{\mathrm{\ell }}^{\mathrm{\prime }}}{\mathrm{\ell }}^{\mathrm{\prime }}$) decays are revisited and completed up to next-to-leading order in QED, finding mild differences with respect to previous studies. These might be relevant for extracting information about the mesons transition form factors, which play an important role in determining the hadronic light-by-light contribution to the anomalous magnetic moment of the muon.