ππ scattering effects in π+p interactions at 8 GeV/ c

Abstract

The reaction π + p → Δ ++π +π − at 8 GeV/ c has been used to study ππ scattering in the ϱ-meson mass region. Two different methods have been used. In the first, it is assumed that ππ scattering in this mass range is entirely elastic and confined to S-, P- and D-waves. The P- and D-waves are assumed to be given by the ϱ 0 and f 0 resonant amplitudes extrapolated off-shell using Dürr-Pilkuhn form factors. The remaining cross section (which by our assumption is S-wave) fits a Breit-Wigner distribution with m S = 680 ± 30 MeV and Γ S 0 = 310 ± 70 MeV. In the second method a ππ phase-shift analysis has been used to obtain the S-wave phase shifts. There are two possible solutions here, one of which resonates at m S = 710 ± a 80 MeV and Γ S 0 = 140 ± 20 MeV.