Resonance in positron-hydrogen scattering at medium energy

Abstract

Higgins and Burke using the R-matrix method indicated the existence of a resonance in the s-wave ground-state capture cross section in positron-hydrogen scattering. Hewitt et al. have confirmed this resonance using the coupled static method. The calculations using the close-coupling approximation (CCA) with six basis sets have been carried out and a resonance is located for each basis. With enlargement of the basis in the expansion scheme, the location of the resonance is shifted towards higher energy. The authors' six-state (H(1s,2s,2p)+Ps(1s,2s,2p)) CCA calculation predicts resonance around 50.0 eV instead of around 20.0 eV as obtained by Hewitt et al using the same basis set.