Instantons and the $\Delta I=1/2$ Rule

Abstract

The instanton induced interaction leads to a significant enhancement of the $A_0$ weak amplitude determining the $\Delta I=1/2$ rule, through the contribution of operators with dimension d=9, as we show in the weak $K\to \pi \pi$ decay.

Comments: 4 pages, 2 figures, Revtex; final version to appear in Phys.Rev.Lett