Resonances in Positron Hydrogen Scattering above the H (n=2) Threshold

We investigate high partial wave resonances in positron-hydrogen scattering using the momentum-space coupled-channels optical method above the H (n=2) threshold. Resonances with angular momenta of L=0–6 are reported. Ionization continuum and positronium formation channels are included via a complex equivalent local potential. Comparisons with the existing theoretical results are presented.