FINAL-STATE INTERACTIONS IN K -] 3PI AND ETA -] 3PI DECAYS

We derive an integral equation which should describe, to a good approximation, the results of any theory of the K and 3 decays. We show that present experimental information implies that one subtraction in this equation is not enough; instead, we find that two subtractions are necessary in order for the equation to describe experiment correctly. We then observe the striking fact that for the weak (K) and electromagnetic () decay processes leading to a 3 final state, the subtraction constants are identical, up to an over-all normalization. A short discussion of the possible significance of this is given, although no definite conclusions are reached. Our analysis confirms the suggestion that final-state interactions will appear only in quadratic terms in the 3 final state. © 1968 The American Physical Society.