G. Compagno et al., PARTIALLY DRESSED STATES AND VANHOVE THEORY OF QUANTUM-FIELDS, Nuovo cimento della Societa italiana di fisica. D, Condensed matter,atomic, molecular and chemical physics, biophysics, 15(2-3), 1993, pp. 355-363
It is shown that Van Hove theory of quantum fields, based on the analy
tic properties of the resolvent operator, is capable of describing a k
ind of non-equilibrium QED states known as partially dressed states. T
his result is obtained by investigating the resolvent description of t
he time development of the bare ground state of the two-level atom rad
iation Hamiltonian using the Coulomb gauge, the minimal coupling schem
e and the electric-dipole approximation.