Single-time equation for a system consisting of a scalar particle and a spinor particle in quantum field theory

A reiativisticalty eovariant method is used to obtain a quasipotential equation and a generalized equation of the Sokolov–Heitler quantum theory of damping from the singletime formulation of the Bethe–Salpeter equation for a system that consists of a scalar particle and a spinor particle. The spin structure of these equations is analyzed and it is shown how the equation of the quantum theory of damping can be reduced to algebraic equations for the partial-wave amplitudes.