Antiproton-hydrogen and antihydrogen-hydrogen annihilation at sub-Kelvin temperatures

The main properties of the interaction of ultra low-energy antiprotons (E l ess than or equal to 10(-6) a.u.) and antihydrogen with atomic hydrogen are established. Elastic and inelastic cross-sections and Protonium formation spectrum are calculated within quantum mechanical coupled channels approach . The results of calculations differ strongly from predictions made by extr apolation of semiclassical models to the energy domain of interest. It is s hown that the main feature of the observables behaviour is determined by ex istence of a family of (p) over bar H, (H) over bar H near-threshold metast able states.