Four-body Calculation of Inelastic Scattering Cross Sections of Positronium–Antihydrogen Collision

We overview our recent calculations of scattering cross sections of positronium–antihydrogen collisions. We discuss the cross sections calculated in the vicinity of the four-body resonances of H ¯ Ps and above the energy threshold for the formation of the antihydrogen positive ions (H ¯ ⁺). In the former energy region where a Rydberg series of resonances dominated by the H ¯ ⁺-e ^- interaction appears, we show a good agreement between the resonant profiles in the cross sections and the resonance energies calculated by the complex coordinate rotation method. H ¯ ⁺ production cross sections near the threshold energy are reported for the positronium being initially in the (n, l) states with n≤ 3 , together with all competing elastic/inelastic cross sections. Comparison of our results with the latest continuum distorted wave final state calculation is presented. A qualitative discrepancy concerning the dependence of cross sections on the angular momentum of Ps is indicated.