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Homework Help: Nuclear physics Pions and Parity?

  1. Feb 9, 2005 #1
    Nuclear physics Pions and Parity? Ignore, nevermind

    Why can:
    \pi^- + d \rightarrow n + n + \pi^0
    not happen for pions at rest?

    work so far:
    {|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
    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
    Last edited: Feb 9, 2005
  2. jcsd
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