Matter-antimatter rearrangements using the R-matrix method

Antihydrogen atoms, (H) over bar, are now routinely created and can be stored for long enough to allow comparison with ordinary matter. A major goal of these efforts is to test potential physics beyond the Standard Model. This will require further developments in the experiments including the accumulation of more antihydrogen atoms and their storage over longer times. The latter is limited by the unavoidable presence of normal hydrogen molecules. Interactions of (H) over bar with H-2 lead to the destruction of the hard-won antimatter. Little is known about these interactions but quantitative information will be crucial in guiding experimental developments. Physically realistic modelling of rearrangement scattering of heavy antimatter particles (antiprotons, (p) over bar, and antihydrogen atoms) by normal matter molecules, such as H-2 + (H) over bar. Pn + Ps + H (where Pn represents protonium and Ps positronium), requires the development of new theoretical and computationalmethodologies. R-matrix theory offers a strong prospect for tackling such problems having proved itself in atomic, molecular and optical physics. It divides the problem into a computationally demanding but energy-independent inner region and simpler energy-dependent outer regions. We propose to adapt the new RmatReact ultracold chemistry approach for the more complex molecular matter-antimatter problems. Here, developments required for the inner region, the boundary and outer regions are outlined. We also report some preliminary bound-state calculations on the {p,p, (p) over bar} system and a study of the required mixed coordinate systems for the general effective 3-body case and their transformations at the R-matrix boundary surfaces.

Automated summary

Antihydrogen atoms can be created and stored for comparison with ordinary matter, contributing to the study of physics beyond the Standard Model. However, the presence of normal hydrogen molecules limits their storage, and more research is needed to understand the interactions between antihydrogen and hydrogen. Physically realistic modeling and new theoretical approaches are required to tackle these problems and guide experimental developments.