One- and Two-Photon Detachment of Ps^- and e^--Ps Scattering Cross Sections

We have computed the single photodetachment cross section of Ps^- in the length, velocity, and acceleration forms for energies below the Ps(n=2) threshold [1]. For the Ps^{- 1}S bound-state we used the Rayleigh-Ritz variational method, whereas for the e^--Ps ¹P continuum we used the complex Kohn variational method. Both the bound-state and continuum wave functions include highly correlated Hylleraas-type terms. Our investigation resolved a discrepancy between a prior calculation of the cross section using a Kohn variational wave function [2,4] and calculations using close-coupling wave functions [5,6]. We have also begun a calculation of the two-photon detachment cross section of Ps^-, in which a discrepancy of four orders of magnitude exists between the two existing calculations [7,8]. Furthermore, we have determined various cross sections for e^--Ps elastic scattering for energies below the Ps(n=2) threshold, namely the elastic differential, elastic integrated, momentum transfer, ortho-para conversion, and viscosity cross sections [1]. For the cross sections we used our complex Kohn ^1,3S-, ^1,3P- and ^1,3D-wave phase shifts.

[1] W. Mitchell and S. J. Ward, Submitted to J. Phys. B: At. Mol. Opt. Phys. (2024).

[2] S. J. Ward and M. R. C. McDowell, Europhys. Lett. 1, 167 (1986).

[3] S. J. Ward, Thesis, University of London, Unpublished (1986), https://repository.royalholloway.ac.uk (date accessed 1/23/2025).

[4] S. J. Ward, J. W. Humberston and M. R. C. McDowell, J. Phys. B 30, 127 (1987).

[5] A. Igarashi, S. Nakazaki, and A. Ohsaki, Phys. Rev. A 61, 032710 (2000).

[6] A. Igarashi, I. Shimamura and N. Toshima, New J. Phys. 2, 17 (2000).

[7] A. Igarashi, J. Phys. B: At. Mol. Opt. Phys. 45, 245201 (2012)

[8] K. Maniadaki, L.A.A. Nikolopoulos, and P. Lambropoulos, Eur. Phys. J. D 20, 205 (2002).