Does The $△I=1/2$ Rule Hold In D And B $\to \pi \pi$ Decays?

Peng Guo, Xiao-Gang He, Xue-Qian Li

Although two pion decays of $K$, $D$ and $B$ have similar isospin structures, there are dramatic differences in the ratios $R_K$ and $R_{D,B}$ of amplitudes from $\Delta I=3/2$ and $ΔI…