Question 31.Q-Q.4: Consider the following decay: π^0 → µ^- + e^+ + νµ . What co...
Consider the following decay: \pi^{0} \rightarrow \mu^{-}+ e ^{+}+\nu_{\mu} . What conservation laws are violated by this decay? (a) energy (b) angular momentum (c) electric charge (d) baryon number (e) electron-lepton number (f) muon-lepton number (g) tau-lepton number (h) no conservation laws
(b), (e), (f). The pion on the left has integral spin, whereas the three spin- \frac{1}{2} leptons on the right must result in a total spin that is half-integral. Therefore, angular momentum (b) is not conserved. There is an electron on the right but no lepton on the left, so electron lepton number (e) is not conserved. There are no muons on the left, but a muon and its neutrino on the right (both with L_{\mu}=+1 ). Therefore, muon lepton number (f) is not conserved.