Spinor-spinor quasipotential in quantum electrodynamics

The quasipotential corresponding to the first variant of the Logunov–Tavkhelidze quasipotential approach is constructed for two interacting spinor fields of equal masses, using relativistically invariant gauges of the Lorentz type. Diagrams of the 2nd order are taken into account and the quasipotential is found in the four-component Dirac and two-component Pauli forms. Low energy bound of two-component representation is obtained. Restoration of the complete structure of the Breit potential is shown in the cases of Landau and Pried and Yennie gauges.