Transverse and Covariant Electromagnetic Propagators: Principal Volume and Self-Field Dyadics
We have realized previously that the longitudinal part of the electric field can be eliminated as a dynamical variable in favour of the particle position coordinates. Such an elimination is particularly important in quantum mechanics where the canonical quantization scheme leads to the association of operators with the position coordinates. When the semiclassical theory of electrodynamics is extended to the quantum electrodynamic level in the Coulomb gauge certain operators are associated with the transverse degrees of freedom of the electromagnetic field. Via the quantization of the transverse part of the free electromagnetic field the photon concept is introduced.