Precision Measurements of the Timelike Electromagnetic Form Factors of Pion, Kaon, and Proton

Abstract

Using $20.7\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ of ${e}^{+}{e}^{\ensuremath{-}}$ annihilation data taken at $\sqrt{s}=3.671\text{ }\text{ }\mathrm{GeV}$ with the $\mathrm{CLEO}\mathrm{\text{\ensuremath{-}}}c$ detector, precision measurements of the electromagnetic form factors of the charged pion, charged kaon, and proton have been made for timelike momentum transfer of $|{Q}^{2}|=13.48\text{ }\text{ }{\mathrm{GeV}}^{2}$ by the reaction ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{h}^{+}{h}^{\ensuremath{-}}$. The measurements are the first ever with identified pions and kaons of $|{Q}^{2}|>4\text{ }\text{ }{\mathrm{GeV}}^{2}$, with the results ${F}_{\ensuremath{\pi}}(13.48\text{ }\text{ }{\mathrm{GeV}}^{2})=0.075\ifmmode\pm\else\textpm\fi{}0.008(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.005(\mathrm{syst})$ and ${F}_{K}(13.48\text{ }\text{ }{\mathrm{GeV}}^{2})=0.063\ifmmode\pm\else\textpm\fi{}0.004(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.001(\mathrm{syst})$. The result for the proton, assuming ${G}_{E}^{p}={G}_{M}^{p}$, is ${G}_{M}^{p}(13.48\text{ }\text{ }{\mathrm{GeV}}^{2})=0.014\ifmmode\pm\else\textpm\fi{}0.002(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.001(\mathrm{syst})$, which is in agreement with earlier results.