S-Matrix Theory and Double Scattering

Abstract

In the double scattering case, we show that the introduction of a pole in the S‐matrix elements, is consistent with a description in terms of successive interactions. We then show that among Olive's class of possible ``propagators'' c(k² ‐ m² + iε)⁻¹ ‐ (1 ‐ c) ·(k² ‐ m² ‐ iε)⁻¹, only the usual value c = 1 gives a consistent result.