A ππ Phase Shift Analysis from an Experiment π−p ⇒ πoπon at 2 GeV/c Supplemented by π+π−, π−πo, π±π± Final States

Abstract

π+π− ⇒ πoπo elastic and differential cross sections from threshold to 1 GeV ππ mass have been obtained by Chew‐Low extrapolation methods from the reaction π−p⇒πoπon at 2 GeV/c. We find large J = 0 production approaching the unitarity limit in the 450–750 MeV ππ mass. An energy‐independent phase shift analysis up to F waves using both the πoπo final state and the already known π±π±, π−πo, π+π− states (giving I = 0,1,2) verifies the overall consistency of the experimental data. Supplemented by the use of forward dispersion relations the phase shift analysis gives a unique solution characterized by the scattering lengths aoo = 0.67 and ao2 = 0.021 and by the presence of an ε (J = I = 0) of mass 940 MeV and width 180 MeV.