S-wave resonances in the positron-hydrogen system with screened Coulomb potentials

We have made a first calculation for S-wave resonances in positron-hydrogen scattering under the influence of Debye plasma environments. A screened Coulomb potential obtained from the Debye model is used to represent the interaction between the nucleus, the electron and the positron. Hylleraas-type wavefunctions are used to represent the correlation effect between the charge particles. The stabilization method is used to calculate the density of resonance states, from which resonance energies and widths are deduced. We have found two resonances of which one is associated with the hydrogen n = 2 threshold, and the other one is found lying below the Ps(2S) threshold. The resonance parameters (energies and widths) calculated for various Debye lengths are reported.