A hard three-loop correction to parapositronium energy levels of order 7 is calculated. This nonlogarithmic contribution is due to the insertions of one-loop photon propagator in the fermion lines in the diagrams with virtual two-photon annihilation. We obtained ΔE = 0.03297(2)(7 / π3) for this energy shift.

Document Type


Publication Date


Notes/Citation Information

Published in Physical Review D, v. 96, issue 1, 011301, p. 1-5.

© 2017 American Physical Society

The copyright holder has granted permission for posting the article here.

Digital Object Identifier (DOI)


Funding Information

This work was supported by the NSF Grant No. PHY-1402593. The work of V. S. was also supported in part by the Russian Foundation for Basic Research Grant No. 16-02-00042.