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Why can:

[tex]

\pi^- + d \rightarrow n + n + \pi^0

[/tex]

not happen for pions at rest?

work so far:

[tex]

\begin{array}

{|c|c|c|c|c|c|}\hline&\pi^-&d&\rightarrow &n \ + \ n&\pi^0\\\hline{Spin}&0&1&\

\rightarrow &1/2 \ 1/2&0\\\hline{J}&0&1&\rightarrow &L + \

S&0\\\hline{Parity}&-1&1&\rightarrow &(-1)^{S+L+1}&-1\\\hline

\end{array}

[/tex]

d is deuterium

S+L for the nuetron pair must be even since they are identical fermions

Partity egeinvalues -1 != 1

I think the Paritiy inequality is the key, but i can not make the connection with a physical law.

Any help would be nice, Thanks

Edit: never mind I figuared it out. Aditional angular momentum on the left hand side will flip parity(l=1,3,5...), making parity conserved again. Thanks anyway

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# Nuclear physics Pions and Parity?

Can you offer guidance or do you also need help?

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