Vacuum-polarization contributions to the spin structure of antiprotonic atoms

The effects of vacuum polarization on the spin structure of the energy levels of $\overline{p}$ atoms are calculated from a new relativistic wave function which includes both recoil and the $\overline{p}$ anomalous magnetic moment. A new value for the $\overline{p}$ magnetic moment is derived, and the changes in the hyperfine structure of protonium are discussed.