S-wave resonance states below the Ps(n=2) threshold in positron-potassium system: Effects of weakly coupled classical plasma and dense quantum plasma

In this paper, the effects of plasmas on the S-wave resonance states in the positron-potassium system are investigated. Two different plasma conditions are considered, namely weakly coupled classical plasma (WCCP) and dense quantum plasma (DQP). The effective interaction potential in WCCP and DQP has been described by the Debye–Hückel model (static screened Coulomb potential) and a modified version of Debye–Hückel model (exponential cosine screened potential). Resonance parameters are determined by calculating the energy-density within the framework of the stabilization method. For the plasma-free case, three states, lying below the Ps[Formula: see text] threshold, are identified. The energy and the width agree well with the existing results in the literature. A detailed study is carried out to explore the changes emerging in the resonance parameters due to screening effects of WCCP and DQP. It is found that the energies of the three states are gradually pushed toward the Ps[Formula: see text] threshold due to the increasing plasma screening strength, whereas widths of the states vary differently.