Coupled channel effects on resonance states of positronic alkali atom

Abstract: S-wave Feshbach resonance states belonging to dipole series in positronic alkali atoms (e⁺Li, e⁺Na, e⁺K, e⁺Rb and e⁺Cs) are studied by coupled-channel calculations within a three-body model. Resonance energies and widths below a dissociation threshold of alkali-ion and positronium are calculated with a complex scaling method. Extended model potentials that provide positronic pseudo-alkali-atoms are introduced to investigate the relationship between the resonance states and dissociation thresholds based on a three-body dynamics. Resonances of the dipole series below a dissociation threshold of alkali-atom and positron would have some associations with atomic energy levels that results in longer resonance lifetimes than the prediction of the analytical law derived from the ion–dipole interaction. Graphical abstract: [Figure not available: see fulltext.].