Question

write selection rules for semi-leptonic and non-leptonic week decays.discuss by using examples and Feynman diagram?

Answer 1

Selection rules for semi-leptonic weak decay:

$$K^-\rightarrow\mu^-+\bar{\nu}_\mu+\pi^0, \\ \Delta S=\Delta Q,\\ \space\\ \frac{\Gamma(K_L\rightarrow\mu^+\mu^-)}{\Gamma(K^+\rightarrow\mu^+\mu^-)}\leq10^{-9}.$$

No $\Delta S$ transitions were experimentally observed.

Selection rules for non-leptonic weak decay:

$$\Delta I=\frac{1}{2},\\ \space\\ \frac{\Gamma(K^+\rightarrow\pi^+\pi^0)}{\Gamma(K_s\rightarrow\pi^+\pi^-)}\approx1.5\cdot10^{-3}.$$