3 Department of Physics, University of Alberta, Edmonton, Alberta T6G 2J1, Canada and Institut für Theoretische Teilchenphysik, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany.
4 Physik Department, Technische Universität München, 85748 Garching, Germany and Institut für Theoretische Teilchenphysik und Kosmologie, RWTH Aachen, 52056 Aachen, Germany.
5 Institut für Theoretische Teilchenphysik, Karlsruhe Institute of Technology, 76128 Karlsruhe, Germany.
We present the complete result for the O(α7me) 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±1 kHz.