Measurement of the properties of theη’and search for other resonances in γγ→ηπ0π0
Abstract
The reaction ${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$\ensuremath{\rightarrow}${e}^{+}$${e}^{\mathrm{\ensuremath{-}}}$\ensuremath{\eta}${\ensuremath{\pi}}^{0}$${\ensuremath{\pi}}^{0}$ has been observed with the Crystal Ball detector at the DORIS II storage ring at DESY. The \ensuremath{\eta}${\ensuremath{\pi}}^{0}$${\ensuremath{\pi}}^{0}$ mass spectrum is dominated by the \ensuremath{\eta}', and the two-photon width ${\ensuremath{\Gamma}}_{\ensuremath{\eta}\mathcal{'}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}}$ is determined to be 4.6\ifmmode\pm\else\textpm\fi{}0.4\ifmmode\pm\else\textpm\fi{}0.6 keV. Limits on ${\ensuremath{\Gamma}}_{X\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}}$\ifmmode\times\else\texttimes\fi{}${B}_{X\ensuremath{\rightarrow}\ensuremath{\eta}\ensuremath{\pi}\ensuremath{\pi}}$ are given for other possible states.
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