The Effect of van der Waals interaction in Elastic Collision between Ps(1s) and H(1s)

TL;DR

This paper investigates how van der Waals interactions influence elastic collisions between positronium and hydrogen atoms at low energies, using a modified static exchange model to analyze phase shifts, cross sections, and potential resonances.

Contribution

It introduces a detailed analysis of long-range van der Waals effects within the MSEM framework for Ps-H collisions, highlighting the sensitivity of scattering parameters to interatomic distance.

Findings

Scattering length is highly sensitive to interatomic potential.

Variation in interatomic distance affects phase shifts and cross sections.

Potential identification of Feshbach resonances in triplet channel.

Abstract

The modified static exchange model (MSEM) recently introduced by Ray [1] to study two-atomic collision processes at low and cold-energies, is used for detailed analysis of the long-range effects due to induced dipole-dipole van der Waals interaction between Ps and H atoms. The MSEM includes the non-adiabatic short-range effect due to electron-exchange and the long-range effect due to induced dynamic dipole polarisabilities of the atoms. The effective interatomic potential is highly sensitive to the minimum distance between the atoms ( ). The s-, p- and d- wave elastic phase shifts, corresponding partial cross sections, the scattering length and effective ranges are calculated and studied with the variation of the chosen least interatomic distance between them. It is found that the scattering length is highly sensitive to the effective interatomic potential that depends on the least interatomic distance. In addition the studies are made in search of Feshbach resonances. The observed interesting feature with the variation of in the triplet channel invites more accurate investigations if new physics.