Calculations of Resonance Parameters for the Doubly Excited 1P° States in Ps- Using Exponentially Correlated Wave Functions

Recent observations on resonance states of the positronium negative ion (Ps(-)) in the laboratory created huge interest in terms of the calculation of the resonance parameters of the simple three-lepton system. We calculate the resonance parameters for the doubly excited P-1 degrees states in Ps(-) using correlated exponential wave functions based on the complex-coordinate rotation method. The resonance energies and widths for the P-1 degrees Feshbach resonance states in Ps(-) below the N = 2, 3, 4, 5 Ps thresholds are reported. The P-1 degrees shape resonance above the N = 2, 4 Ps thresholds are also reported. Our predications are in agreement with the available results. Few Feshbach resonance parameters below the N = 4 and 5 Ps thresholds have been reported in the literature. Our predictions will provide useful information for future resonance experiments in Ps(-).