arXiv:1911.10931 · Physical Review A
Quasibound states of an antiproton and a hydrogen atom
D. Baye, Jérémy Dohet-Eraly
Abstract
Accurate three-body quantal calculations of the system composed of a proton, an antiproton, and an electron are performed in perimetric coordinates with the Lagrange-mesh method, an approximately variational calculation with the simplicity of a calculation on a grid. Quasibound states with respect to the $\overline{p} + \mathrm{H}(n=2$) threshold are obtained for $L=60\ensuremath{-}73$ for various vibrational excitations. Their energies have accuracies up to about ${10}^{\ensuremath{-}14}$ atomic units, while less precise energies are determined for $L=56--59$ broader resonances. Their structure is analyzed with the help of mean distances between the particles. These mean distances indicate that the proton-electron subsystem is in excited states, mostly $n=2$, as predicted by Sakimoto [Phys. Rev. A 98, 042503 (2018)] with the Born-Oppenheimer approximation. A comparison performed with this approximation provides the accuracies of its energies and of its proton-antiproton mean distances.