Full quantum-mechanical study of protonium formation in slow collisions of antiprotons with hydrogen atoms

A rigorous full quantum-mechanical wave-packet calculation is carried out to study the protonium formation p̅ +H→p̅ p+e. The present paper directly solves the time-dependent Schrödinger equation for the heavy particle Coulomb collision system. A discrete-variable-representation technique is used to evaluate the action of the Hamiltonian operator on the wave packet. The cross sections for the protonium formation are obtained at center-of-mass translational energies up to 10 eV. The present quantum-mechanical results are compared with those of previous studies based on classical trajectory Monte Carlo and semiclassical methods. Applicability of the adiabatic molecular picture to the protonium formation is also discussed.