Partial-wave analysis of the ηπ0π0 system produced in π-p charge-exchange collisions at 100 GeV/c

The spin-parity of the ηπ0π0 system from the charge-exchange transition π-p→ηπ0π0n is analyzed for mass values up to 1.9 GeV. Data used in this analysis come from the GAMS-4000 multiphoton spectrometer irradiated by a 100-GeV/ cπ- beam of the SPS accelerator at CERN. Experimental mass spectra show distinct signals from the pseudoscalar mesons η(1295) and ι/η(1440) and from the axial-vector meson D/f1(1285). The values found for their masses and widths agree well with the world-average values. The cross sections for the production of the above mesons are measured, and the relative branching fractions for some of their decays are estimated. The decay η(1295)→ ηπ0π is found to be dominated by the a0(980)π0 channel. On the other hand, the decay ι/η(1440)→a0(980)π0 is dominated by the η(π0π0)s channel, whereas the a0(980)π0 contribution is small. This suggests that ι is an exotic meson with a significant component of valence gluons