Delta I = 1/2 enhancement and the Glashow-Schnitzer-Weinberg sum rule

Abstract

In 1967 Glashow, Schnitzer and Weinberg derived a sum rule in the soft-pion and soft kaon limit relating the Delta I=1/2 non-leptonic K->2pi amplitude to integrals over strange and non-strange spectral functions. Using the recent ALEPH data from tau-decay, we show that the sum rule, slightly modified to reduce contributions near the cut, yields the correct magnitude decay amplitude corresponding to the Delta I=1/2 rule.