Coupled-channels optical calculation of positron—hydrogen resonances

Abstract

An application of the coupled-channels optical method is given for the energy-dependent phenomena of positron-hydrogen resonances below the n = 2 excitation threshold. The equivalent local optical potential is used to account for the target polarization and positronium formation. The calculation includes 9 explicitly physical coupled channels. The lowest S-wave resonance energy position and new resonances are found. Angular dependence of the cross section in the resonance region are investigated.

Resonance phenomena and threshold features in positron—helium scattering

“…The method has been applied to calculate various scattering cross sections (positronium formation, ionization, and total scattering cross sections) for the positron-atom systems, and satisfactory results have been obtained comparing with the experimental data and the other theoretical results. [23−25] Recently, the method has also been applied to investigate the resonance phenomena in positron-atom [14,26] systems. In the present work, s-, p-, and d-wave resonances in the positronhelium system have been determined, and the cusp features at the thresholds of Ps (n = 1, 2) have been found.…”

Differential cross sections of positron–hydrogen collisions

“…A detailed theoretical description of the CCO method has been given in the paper of Zhou et al [25] and also in our previous work. [32][33][34] Here we outline the essential features of this method. The total scattering cross section is calculated by solving the momentum-space coupled-channels equations [26] 𝑘…”

“…Recently, the CCO method for positron-atom scattering given by Zhou et al [25] has been applied to study the energy-dependent phenomena in positronatom systems. [30][31][32][33][34] In our previous work, [32,33] the energydependent phenomena and the resonance structures in the positron-hydrogen system have been studied in the framework of the CCO model. An equivalent local polarization potential has been used to describe the target ionization continuum and the positronium (Ps) formation rearrangement channels and therefore this method can ideally take the contributions of all reaction channels into account.…”

“…The method has been applied to calculate various scattering cross sections (positronium formation, ionization, and total scattering cross sections) for the positron-hydrogen system and satisfactory results have been obtained comparing with experimental data and other theoretical calculations. [32,33]…”

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

“…Using this method, we study the resonance phenomena in the positron-hydrogen system below the H (𝑛 = 2) threshold. [16] We obtain the lowest S-wave resonances and identify some new resonances. Our results show that a larger close-coupling scheme can shift the position of resonance away from the opening channel threshold.…”