Analysis of the 33-133-133-1final state in photon-photon collisions

The reactione+e- →e+e- ηπ0π0→e+e- 6γ has been analysed using the full data sample taken with the Crystal Ball detector at the DORIS II storage ring at DESY. The ηπ0π0 invariant mass spectrum is dominated by the η', for which we determine the radiative width Γγγ(η') to be (4.5±0.3±0.5)keV. Near 1.9 GeV/c2 we observe a second enhancement in the ηπ0π0 mass distribution. Assuming that these events are created by the production and subsequent decay of a wide resonanceX(1900), we have investigated the decay modes, the invariant mass distributions of the ηπ0 and π0π0 subsystems and the angular distributions of the final state mesons. We find that the data is best described byJPC=2∓. For thisJP assignment the resonance parameters are Γγγ(X) BR(X→ηππ)=(0.95±0.27±0.20) keV Γtot (X)=(221±92±44)MeV, andM(X)=(1881±32±40) MeV/c2.