## Abstract

By recasting the Bethe-Salpeter equation in a more general form, the natural ensuing bound-state perturbation theory accounts for the anomalous α6lnα-1 contribution of the fourth-order vacuum polarization to the ground state of the positronium hyperfine structure as a binding correction of a two-photon diagram. Viewed as such, this contribution is not anomalous. Another two-photon diagram, in which such a binding correction makes it a candidate for an α6lnα-1 contribution, is found. By using the Bethe-Salpeter equation recast in the more general form and the perturbation theory associated with it, the formal connection with the external field approximation is given.

Original language | English |
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Pages (from-to) | 452-456 |

Number of pages | 5 |

Journal | Physical Review A |

Volume | 16 |

Issue number | 1 |

DOIs | |

State | Published - 1 Jan 1977 |

## ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics