Measurement of π−p→π0π0n at 25 GeV/c

The reaction π−p→π0π0n has been measured with a 648 channel hodoscope spectrometer for the detection of the four γ's from the π0 decays. The π0π0 D-wave is fully compatible with the f0 contribution as it is determined in high-statistics π+π− experiments. The magnitude of the π0π0 S-wave and the cosinus of its phase angle (relative to the known D-wave) are determined from fits to the π0π0 angular distributions. Argand diagrams for the I = 0 amplitude S0 are given for the range 1000 to 1500 MeV/c2. Two solutions exist. One exceeds the unitarity limit above 1200 MeV/c2. The other remains within the unitarity limit and is nearly elastic up to 1450 MeV/c2. It indicates an S0 wave resonance around 1300 MeV/c2.