You need to log in to answer this problem. Why can the photon propagator In line with Faddeev & Popov be employed as replacement for vacuum expectation from the two-position correlator? And also more raises questions about the value from the Altitude Reserve (I can't believe I mentioned that!) https://thcareview34443.elbloglibre.com/39715650/the-smart-trick-of-read-more-that-nobody-is-discussing