Positronium formation cross-sections in the ground and excited states ( $\mathsf{n=2}$ levels) in an $\mathsf{e^{+}}$ -He atom collision

Abstract

The positronium formation cross-sections in the ground and excited n=2 levels have been studied in an -He atom collision in the framework of eikonal approximation. Both the differential and total formation cross-sections have been investigated in the intermediate- and high-energy regime. Present eikonal results are found to differ appreciably from the corresponding first Born values even at very high incident energies. The total cross-section results have been compared with available experiments due to different groups as well as with other existing theoretical results.