Hyperfine splitting in positronium to ${\cal O}(α^7m_e)$: one-photon annihilation contribution
arXiv:1402.0876 · doi:10.1103/PhysRevLett.112.120407
Abstract
We present the complete result for the ${\cal O}(α^7m_e)$ one-photon annihilation contribution to the hyperfine splitting of the ground state energy levels in positronium. Numerically it increases the prediction of quantum electrodynamics by $217\pm 1$ kHz.
5 pages, 2 figures