Antiproton capture by lithium atoms ($\overline{p}+\mathrm{Li}\to \overline{p}{\mathrm{Li}}^{+}+e$) is investigated at collision energies from $0.01$ to 10 eV by using a semiclassical (also know as quantum-classical hybrid) method, in which the radial distance between the antiproton and the Li${}^{+}$ ion is treated as a classical variable, and the other degrees of freedom are described by quantum mechanics. Analyzing the wave packet of the emitted electrons and making use of the energy conservation rule enable us to calculate the state distribution of the produced antiprotonic lithium $\overline{p}{\mathrm{Li}}^{+}$ atoms and also to distinguish between the capture and ionization ($\to \overline{p}+{\mathrm{Li}}^{+}+e$) channels at collisional energies above the ionization threshold. This method is tested for the capture of negative muons by hydrogen atoms, which was rigorously investigated in previous quantum mechanical studies. Most of the $\overline{p}{\mathrm{Li}}^{+}$ atoms produced in $\overline{p}+\mathrm{Li}$ are found to be sufficiently stable against Auger decays and are experimentally observable as long-lived states. The present system bears close similarities to the system of $\overline{p}+\mathrm{He}\left(2S\right)$. It is therefore expected that long-lived antiprotonic helium $\overline{p}{\mathrm{He}}^{+}$ atoms can be efficiently produced in the $\overline{p}$ capture by metastable He($2{}^{3}S$) atoms.

• Received 22 June 2011

DOI:https://doi.org/10.1103/PhysRevA.84.032501