A data-driven approach to ${\pi }^0,\eta$ and ${\eta }^{\prime }$ single and double Dalitz decays

Abstract

The dilepton invariant mass spectra and integrated branching ratios of the single and double Dalitz decays $\mathcal{P}\to {\ell }^{+}{\ell }^{-}\gamma$ and $\mathcal{P}\to {\ell }^{+}{\ell }^{-}{\ell }^{+}{\ell }^{-}$ ($\mathcal{P}={\pi }^0,\eta ,{\eta }^{\prime }$; $\ell =e$ or $\mu$) are predicted by means of a data-driven approach based on the use of rational approximants applied to ${\pi }^0,\eta$ and ${\eta }^{\prime }$ transition form factor experimental data in the space-like region.

Comments: 18 pages, 11 figures. This version matches the published version