Full Quantum Mechanical Study of Protonium Formation in Slow Collisions of Antiprotons with Hydrogen Atoms

A rigorous full quantum mechanical wavepacket calculation is carried out for the protonium formation + H → p + e. The cross sections for the protonium formation are obtained at center-of-mass collision energies up to 10 eV. Also carried out is a semiclassical (quantum-classical hybrid) calculation to make a physical interpretation of the quantum mechanical result. An empirical fitting law is proposed for the relation between the formation probability and the turning point of the relative motion, and is found to be very useful in estimating the formation cross section at low energies.