$ππ$ scattering S wave from the data on the reaction $π^-p\toπ^0π^0n$

Abstract

The results of the recent experiments on the reaction $π^-p\toπ^0π^0n$ performed at KEK, BNL, IHEP, and CERN are analyzed in detail. For the I=0 $ππ$ S wave phase shift $δ^0_0$ and inelasticity $η^0_0$ a new set of data is obtained. Difficulties emerging when using the physical solutions for the $π^0π^0$ S and D wave amplitudes extracted with the partial wave analyses are discussed. Attention is drawn to the fact that, for the $π^0π^0$ invariant mass, m, above 1 GeV, the other solutions, in principle, are found to be more preferred. For clarifying the situation and further studying the $f_0(980)$ resonance thorough experimental investigations of the reaction $π^-p\toπ^0π^0n$ in the m region near the $K\bar K$ threshold are required.