AMPLITUDE ANALYSIS OF DATA ON (P)OVER-BAR-P-]PI-PI AT LOW-ENERGY

The first amplitude analysis of data on ppBAR --> pi-pi+ from the PS172 experiment at CERN's LEAR facility is performed to discover the resonant content of the NNBAR --> pipi channel in the range 0.36 less-than-or-equal-to P(lab) less-than-or-equal-to 1.55 GeV/c. Simultaneously fitting existing data on ppBAR --> pi0pi0, we find just two solutions having acceptable threshold behaviour and continuity in energy. Resonant structures in these solutions are studied using self-consistency to fix the arbitrary overall phase of the amplitudes. Both solutions exhibit a rich spectrum of resonances with spins from 0 to 4. This includes at least one state, with J(PC) = 0++, whose coupling to NNBAR is much larger than would be expected for a simple qqBAR state.