Energy-dependent partial-wave analysis of all antiproton-proton scattering data below 925 MeV/c

Background: There is a renewed experimental interest in antiproton-proton scattering with an intense, possibly polarized antiproton beam. On the theoretical side, significant progress has been made in the understanding of the nuclear force from chiral effective field theory.Purpose: We provide a high-quality model-independent description of the available low-energy antiproton-proton scattering data.Method: We perform a new energy-dependent partial-wave analysis of all antiproton-proton elastic (p¯p→p¯p) and charge-exchange (p¯p→n¯n) scattering data below 925 MeV/c antiproton laboratory momentum. The Schrödinger equation is solved for the coupled p¯p and n¯n channels. The relevant long-range parts of the electromagnetic and the one- and two-pion exchange interactions are included exactly. The short-range interactions, including the coupling to the mesonic annihilation channels, are parametrized by a complex boundary condition at a radius of r=1.2 fm.Results: The updated database, which includes significantly more high-quality charge-exchange data, contains 3749 scattering data. The fit gives χ_min²/N_df=1.048, where N_df=3578 is the number of degrees of freedom. We discuss the description of the experimental data and we present the antiproton-proton phase-shift parameters.Conclusions: Chiral effective field theory provides an excellent long-range antinucleon-nucleon interaction. The results of the PWA should serve as the starting point for future theoretical and experimental investigations of low-energy antiproton-proton scattering.