Question

Is Schrieffer-Wolff transformation equivalent to Feynman diagram and Path integral?

Answer 1

Concerning the path integral, there is no problem with integration over too long ... included in Feynman's sum - can never be harassed by similar conditions..

Answer 2

In high energy community, people usually use path integral (or Feynman diagram) to derive effective action (or effective Hamiltonian). However, in condensed matter or AMO community, people usually use Schrieffer-Wolff transformation to derive it.