What interactions are involved in these particle decays?

[latentcorpse]

justify which interactions is involved in each of the following:

$\pi^0 \rightarrow \gamma \gamma$
$\pi^+ \rightarrow \mu^+ \nu_\mu$
$\pi^- p \rightarrow \triangle (1232) \rightarrow \pi^0 n$
$K^0 \rightarrow \pi^+ \pi^-$
ok the first one i ruled out strong force since particles on right don't have colour charge. i ruled out weak netural currecnt (Z boson) interaction since fermion flavour isn't conserved. so its between weak charged current ( $W^{\pm}$ boson) or electromagnetic). i think it's probably W boson since photons don't have charge so you can't have a vertex on the Feynman diagram with three photons meeting. is this right?

for the second one, i ruled out strong force and Z boson for same reasons as above. this time, seeing as they are charged, i don't know how to decide between W boson or electromagnetic? any ideas?

i have no clue for the third one since i don't know what $\triangle (1232)$ is.

the fourth one I am not sure about either but i have the feeling its a weak interaction. posisbly a W boson since the fermion flavour does change. but I am not sure whether its W+ or W- or how to rule out the strong and electromagnetic interactions.

thanks.

 

[NateD]

For the first interaction, it is a weak charged current interaction mediated by the W boson. For the second interaction, it is also a weak charged current interaction mediated by the W boson. For the third interaction, it is likely a strong force interaction. The \triangle (1232) is an excited state of a nucleon, and the strong force is responsible for the interactions between nucleons. For the fourth interaction, it is likely a weak interaction mediated by the W boson. The fermion flavour does change, and the strong force does not interact with the K^0 since it is a neutral particle.