# Hadronic Decays (Homework 5, Physics 226)

5. Hadronic decays. Indicate which of the particles listed in tables 5.3-5.6 of the course notes do not decay via strong interactions. Which of these decays involve weak interactions? Which are electromagnetic decays? For which decays is the dominant interaction responsible for the decay ambiguous? Explain your reasoning.

Here the rules are:

-mesons $π$ are characteristic to strong interaction decays

-neutrinos $ν$ are characteristic to weak interaction decays

-photons $γ$ are characteristic to electromagnetic interactions decays

Therefore for example from table 5.3

$π^0$ decays through EM interaction $π^0→γ+γ$

$π^+$ and $π^-$ decay though weak interactions ,$π^+→μ^++ν_μ$

$K^+$ and $K^-$ first decays are also through weak interactions $K^+→μ^++ν_μ$

Where ever there is a mix of $π,ν$ (and/or) $γ$ in the products of the decay the decays are ambiguous. For example the decay

$K_L^0→π^±+e^∓+ν_e$

Also the decay is ambiguous when the particles above are missing from the reaction products. For example in table 5.4

$ϕ→K^++K^-$