A Self-Consistent Model for Positronium Formation from Helium Atoms

TL;DR

This paper develops a self-consistent first-order distorted wave model to calculate positronium formation cross sections from helium atoms, aligning well with experimental data and improving theoretical accuracy.

Contribution

It introduces a self-consistent formalism using a parametric potential that satisfies boundary conditions and electron screening effects for positronium formation calculations.

Findings

Results agree well with recent experiments.

The model provides a realistic description of electron screening.

The approach improves upon previous theoretical methods.

Abstract

The differential and total cross sections for electron capture by positrons from helium atoms are calculated using a first-order distorted wave theory satisfying the Coulomb boundary conditions. In this formalism a parametric potential is used to describe the electron screening in a consistent and realistic manner. The present procedure is self consistent because (i) it satisfies the correct boundary conditions and post-prior symmetry, and (ii) the potential and the electron binding energies appearing in the transition amplitude are consistent with the wave functions describing the collision system. The results are compared with the other theories and with the available experimental measurements. At the considered range of collision energies, the results agree reasonably well with recent experiments and theories. [Note: This paper will be published on volume 42 of the Brazilian Journal of Physics]