Low-energy scattering properties of ground-state and excited-state positronium collisions

Abstract

Synopsis Low-energy elastic and inelastic scattering in the Ps(1s)-Ps(2s) channel is treated in a four-body hyperspherical coordinate calculation. Adiabatic potentials are calculated for triplet-triplet, singlet-singlet, and singlet-triplet spin symmetries of coupled electrons and coupled positrons, with total angular momentum L = 0 and positive parity. Preliminary estimates of the s-wave scattering length in the elastic Ps(1s)-Ps(2s) channel were obtained. Spin recoupling is implemented to obtain calculations of experimentally relevant scattering properties for different Ps spin states.