Resonance states of Ps- using correlated wave functions
Abstract We have investigated the F e 1 , 3 resonance states of positronium negative ion below the N = 3 , 4 and 5 Ps thresholds using highly correlated exponential wave functions. Resonance parameters (positions and widths) are extracted employing both the stabilization method and the complex-coordinate rotation method. In addition to many Feshbach resonances below the various Ps thresholds, we have identified two F e 1 shape resonances with one each lying above the N = 3 and N = 5 thresholds, respectively. We have also identified three F e 3 shape resonances with one lying above the N = 3 threshold and two lying above N = 4 threshold. The F e 1 , 3 shape resonances associated with N = 3 Ps threshold and some other Feshbach resonances are reported for the first time in the literature.
Doubly Excited 1,3Pe Resonance States of the Positronium Negative Ion with Coulomb and Screened Coulomb Potentials
We have investigated the doubly excited 1,3Pe resonance states of positronium negative ion with Coulomb and screened Coulomb potentials using highly accurate correlated exponential wavefunctions. For Coulomb interaction, the stabilization and the complex-rotation methods are employed to extract resonance parameters (resonance positions and widths). We have obtained two 1Pe resonances and three 3Pe resonances below the n = 3 Ps threshold. In addition to Feshbach resonances lying below n = 3 Ps threshold, we have calculated one 3Pe shape resonances lying above the Ps (n = 2) threshold. For screened Coulomb (Yukawa) interaction, we employ the stabilization method to extract resonance parameters as functions screening parameter. The resonance energies and widths for 1,3Pe resonance states of Ps− below the n = 3 Ps threshold for different screening parameters ranging from infinity (Coulomb case) to small values are reported, along with the Ps(3S) and Ps(3P) threshold energies. The screened Coulomb results for the 1,3Pe resonance states are reported for the first time in the literature.
Possible effects of positronium negative ion on 0.511 MeV ψ-ray line in astrophysical sources
The astrophysical importance of the negative positronium ion, detected recently in the laboratory, has been pointed out. It is found that the presence of Ps− ions will contribute additionally to the width of 0.511 ψ-ray line formed by pair annihilation. The formation of Ps− ion from an aggregate of electrons, positrons and positronium results in a variable positron population in the 0.511 MeV ψ-ray line source.