0000000000459539
AUTHOR
Sergi Gonzàlez-solís
η′transition form factor from space- and timelike experimental data
The ${\ensuremath{\eta}}^{\ensuremath{'}}$ transition form factor is reanalyzed in view of the recent first observation by BESIII of the Dalitz decay ${\ensuremath{\eta}}^{\ensuremath{'}}\ensuremath{\rightarrow}\ensuremath{\gamma}{e}^{+}{e}^{\ensuremath{-}}$ in both space- and timelike regions at low and intermediate energies using the Pad\'e approximants method. The present analysis provides a suitable parametrization for reproducing the measured form factor in the whole energy region and allows one to extract the corresponding low-energy parameters together with a prediction of their values at the origin, related to ${\mathrm{\ensuremath{\Gamma}}}_{{\ensuremath{\eta}}^{\ensuremath{'}}\ens…
Phenomenological applications of rational approximants
We illustrate the powerfulness of Padé approximants (PAs) as a summation method and explore one of their extensions, the so-called quadratic approximant (QAs), to access both space- and (low-energy) time-like (TL) regions. As an introductory and pedagogical exercise, the function [Formula: see text] is approximated by both kind of approximants. Then, PAs are applied to predict pseudoscalar meson Dalitz decays and to extract [Formula: see text] from the semileptonic [Formula: see text] decays. Finally, the [Formula: see text] vector form factor in the TL region is explored using QAs.