Quenching of $para$-H$_2$ with an ultra-cold anti-hydrogen atom $\bar{H}_{1s}$

TL;DR

This study calculates quantum-mechanical rotational transition cross sections and rate coefficients for H$_2$ molecules induced by ultra-cold anti-hydrogen atoms, providing insights into cold molecular collision processes.

Contribution

It presents the first detailed quantum-mechanical calculations of rotational transitions in H$_2$ caused by ultra-cold anti-hydrogen, using a close-coupling approach.

Findings

Calculated elastic and inelastic cross sections agree with previous variational results.

Provided temperature-dependent rate coefficients for 0.004 K to 4 K.

Enhanced understanding of cold H$_2$-anti-hydrogen collision dynamics.

Abstract

In this work we report the results concerning calculations for quantum-mechanical rotational transitions in molecular hydrogen, H$_2$, induced by an ultra-cold ground state anti-hydrogen atom $\bar{H}_{1s}$. The calculations are accomplished using a non-reactive close-coupling quantum-mechanical approach. The H$_2$ molecule is treated as a rigid rotor. The total elastic scattering cross section $\sigma_{el}(\epsilon)$ at energy $\epsilon$, state-resolved rotational transition cross sections $\sigma_{jj'}(\epsilon)$ between states $j$ and $j'$ and corresponding thermal rate coefficients $k_{jj'}(T)$ are computed in the temperature range 0.004 K $ \lesssim T \lesssim$ 4 K. Satisfactory agreement with other calculations (variational) has been obtained for $\sigma_{el}(\epsilon)$.