Violation Of The $\mathrm{\Delta }I=1\mathrm{/}2$ Rule In $D\to \pi \pi$ Decays

A strong violation of the ${\displaystyle \mathrm{\Delta }I=\frac{1}{2}}$ rule has experimentally been found in the ${\displaystyle D\to \pi \pi }$ decays [1]. In this letter we will show that the order of magnitude of this violation can be understood in terms of the pure quantum chromo dynamics corrections to the weak interactions.