On the expansion of the propagator in power series of the coupling constant
R.B. Perez · Journal of Mathematical Physics · 1979
We show by simple rearrangements of the Lippmann–Schwinger equation, that the propagator (Green’s function) of a linear physical field can be expanded in power series valid for values of the coupling constant either close to unity or very large. The new series satisfy the generalized resolvent operator equation first derived by Mockel.