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Why do muons decay?

  1. Jul 14, 2008 #1
    In all the books i've been reading it just states that muons are unstable and that they decay into an electron and a neutrino (all be it with a relatively long life-time compared to some other particles). But it says nothing about why the muon actually decays. I assume it's something to do with it wanting to lower its energy but i'd like to know a bit more detail if I could.

  2. jcsd
  3. Jul 14, 2008 #2


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    You are correct, the electron is a ligher particle and the muon can decay to it, and will do it.


    You can naively think of this as the excited atom: The extited atom has higher mass then the atom in its ground state (since the electron has gained energy so it can occupy a higher state), the excited state can and will decay to the ground state again.
  4. Jul 14, 2008 #3


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    On the same token, Nature abhors vacuum and because of it the quicksilver will ascend the tube.

    The good question is "how many centimeters?". Or here, "at what rate?"
  5. Jul 14, 2008 #4
    Okay cool, thanks. So unnecessarily high energy levels and vacuum. Anything else? :p
  6. Jul 14, 2008 #5


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    A key point is that the process occurs (at tree level) because in the Standard Model there is a term that couples those particle together to a W minus boson (the story is actuallly a bit more subtle but that's the basic point). If there was no such term, the process might still occur but it would be much rarer (so the lifetime would be much longer) because it could only occur with Feynman diagrams containing loops which suppress the process.
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