Nonleptonic decays of K mesons revisited
  We estimate nonfactorizable 1/$N_c$ contributions in the $K\rightarrow 2\pi$ amplitudes using the approach proposed in our previous work. It is demonstrated that for the conventional (nonpenguin) operators these contributions are close in magnitude to factorizable $1/N_c$ parts and have the opposite sign. Thus, an approximate rule of discarding $1/N_c$ corrections in $K\rightarrow 2\pi$ decays is theoretically confirmed. As a result we find an extra suppression of the matrix element of $O_4$ ($\Delta I=3/2$) and an extra enhancement of the matrix element of $O_1$ ($\Delta I=1/2$).   The parameter $B$ describing $K^0-\bar K^0$ mixing is also discussed. 
B. Blok and M. Shifman