Remarks on the Calculation of the Enhancement Factor in the K -> 2 pion   Decay
  The problem of calculation of the enhancement factor due to the strong pion final state interaction is reexamined in the light of recent interest in understanding of the origine of the $\Delta I=1/2$ rule and calculations of the CP violation parameter $\epsilon^{\prime}/\epsilon$. It is shown that the traditional method of calculating the \emph{absolute} enhancement factor is model dependent, while the method of relating $K \to 2\pi$ amplitude to the $K-\pi$ matrix element using Current Algebra is on a safer ground. 
Tran N. Truong