C ⁣PC\!P violation in η\eta muonic decays

In this study, we investigate the imprints of $C\!P$ violation in certain $\eta$ muonic decays that could arise within the Standard Model effective field theory. In particular, we study the sensitivities that could be reached at REDTOP, a proposed $\eta$ facility. After estimating the bounds that the neutron EDM places, we find still viable to discover signals of $C\!P$ violation via the muons' polarization in $\eta\to\mu^+\mu^-$ decays at REDTOP, with a single effective operator as its plausible source.Comment: 18 pages, 5 figures. Matches the published version in JHEP; contains minor changes in Appendix

η\eta and η′\eta' transition form factors from Pad\'e approximants

We employ a systematic and model-independent method to extract, from space- and time-like data, the $\eta$ and $\eta'$ transition form factors (TFFs) obtaining the most precise determination for their low-energy parameters and discuss the $\Gamma_{\eta\rightarrow\gamma\gamma}$ impact on them. Using TFF data alone, we also extract the $\eta-\eta'$ mixing parameters, which are compatible to those obtained from more sophisticated and input-demanding procedures.Comment: 4 pages, 2 figures, presented at the 13th International Workshop on Meson Production, Properties and Interaction (MESON 2014); added reference