Coulomb interaction correction to the vacuum polarization tensor in a super-strong magnetic field

The effect on the vacuum polarization tensor of including a Coulomb interaction between the virtual electron-positron pairs is studied. The basic formalism required to obtain an explicit expression for the higher order vacuum polarization tensor in a magnetic field is initially performed. This approach is based on the theory of quantum electrodynamics, modified to include the effects of the magnetic field exactly. It is found that with Coulomb interaction included, the vacuum response displays a stronger resonance behaviour than is otherwise the case. This behaviour qualitatively agrees with the results obtained by Shabad and Usov, who examined vacuum polarization in the case where the virtual pair is mutually bound by Coulomb interactions. This study provides independent confirmation that the photon capture effect is enhanced by including higher order effects in the vacuum polarization. (author)