According to Complete Relativity (an improvement of Special Relativity where a new postulate was introduced: an electron cannot move at average speeds less than u0 = αc / π where α is the constant of fine structure and c is the speed of light), and with the hypothesis that the electron and positron are two three-dimensional electromagnetic spherical standing waves, the electromagnetic standing waves of an electron-positron pair can overlap in the low energy conditions and generate a single γ ray of E = 1.022 MeV. Instead the actual physical theories consider a model of positron-electron pair annihilation, where conservation of momentum requires the creation of two 511 keV photons moving toward opposite directions. But in the paper we do not consider any photons: there is only a progressive electromagnetic wave compound by two electromagnetic standing waves. Only a thorough test will be able to decide the right model.