Low-energy positron scattering from metastable helium
Phys. Rev. A 114, 042808 – Published 13 October, 2026
DOI: https://doi.org/10.1103/6m7n-md66
Abstract
Low-energy positron scattering from singlet and triplet metastable He() is investigated using the -matrix propagation method in hyperspherical coordinates. Elastic and positronium-formation cross sections are reported, and near-threshold resonance structures are analyzed in terms of eigenphase sums and the time-delay matrix. For the triplet target, the calculated cross sections are in agreement with available convergent-close-coupling results and display the expected threshold behavior. Beyond the known -wave features, Feshbach resonance series in higher partial waves extending up to highly excited atomic thresholds are systematically identified. The time-delay matrix further uncovers hidden resonances that produce obvious structures in the positronium-formation cross sections.
