Abstract
The value of vacuum-polarization amplitude is investigated in the region of positronium bound-state poles, where the naive Feynman-graph expansion fails. The corresponding contribution to positronium-ground-state splitting is explicitly evaluated up to order . The previously given result for the term coming from fourth-order vacuum-polarization corrections to the one-photon annihilation diagram is confirmed and put on a sounder basis. The term is found to receive, besides the obvious contribution from vacuum-polarization term, an additional -contribution which can be considered as generated by an infinite series of terms of higher nominal order in .
- Received 1 March 1973
DOI:https://doi.org/10.1103/PhysRevA.8.2266
©1973 American Physical Society