2025/11/14 by Gao, Ning-Ning, Han, Hui-Li, Shi, Ting-Yun +1
#Atomic Physics (physics.atom-ph) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2511.11084
We investigate resonances in positron-sodium scattering using the R-matrix propagation method formulated in hyperspherical coordinates. The interaction between the sodium core and the valence electron is described by analytical model potentials. High partial-wave resonances are calculated for collision energies up to the Na(4f) threshold. Several resonant states of debated character are identified, and their behavior is analyzed through phase-variation studies, the associated structures in the calculated cross sections, and the characteristic patterns observed in the stability plots. The calculated dipole series of resonances, supported by the ion-dipole interaction between Na\scriptscriptstyle+ and Ps(n=2), shows good agreement with recent complex-scaling calculations. In addition, a sequence of quasi-dipole resonances is found to arise from the near degeneracy of the Na(4d) and Na(4f) states in the e+-Na system, which accumulate geometrically toward the Na(4d) threshold.