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) over barp -> (p) over barp) and charge-exchange ((p) over barp -> (n) over barn) scattering data below 925 MeV/c antiproton laboratory momentum. The Schrodinger equation is solved for the coupled (p) over barp and (n) over barn 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 chi(2)(min)/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.