Recent results on antiproton-proton cross sections at small momenta

The antiproton-proton cross sections for elastic scattering, charge-exchange reaction (anti pp → anti nn), and annihilation have been measured in the beam momentum range between 180 and 600 MeV/c. The partial wave components in elastic and inelastic cross sections are derived from the analysis of differential elastic cross sections. It is found that there is a large contribution of p-wave even at 180 MeV/c, in contrast to NN interactions where s-wave is dominant. The range of annihilation and the range charge-exchange reaction are evaluated by a model with one-pion-exchange potential and a short-range complex Woods-Saxon potential. It is shown that antiproton-proton annihilation takes place at the distance of around 1 fm, while the charge-exchange reaction is sensitive to the region up to 4 fm. This analysis could provide an approach to the quark-confinement problem in baryons. (orig.)