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B Neutral pion decay

  1. Apr 2, 2016 #1
    Hi everyone,
    I am curious about how a neutral pion decays in two photons. I don't understand how it is possible since the pion has spin = 1 and the photons have spin = 1 as well: doesn't this mean that spin is not conserved in this decay? What am I missing?

    Another question I have is about spin: do anti-particles and anti-quarks have negative spin, or is the spin always positive?

    Sorry for the silly questions and thanks to everyone in advance :)
     
  2. jcsd
  3. Apr 2, 2016 #2

    PeroK

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    Perhaps the pion doesn't have spin 1? If the pion has spin 0, say, that might indeed make it a silly question.
     
  4. Apr 2, 2016 #3

    Vanadium 50

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    How sure are you that the pion has spin 1?
     
  5. Apr 2, 2016 #4

    Orodruin

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    Apart from this, it is perfectly possible for two spin-1 particles to couple to a spin-1 so even if the pion had spin 1 it would not be that strange.
     
  6. Apr 2, 2016 #5

    Vanadium 50

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    Actually, a spin-1 particle cannot decay to two photons. See Yang, Physical Review 77: 242–245 (1950).
     
  7. Apr 2, 2016 #6

    Orodruin

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    Not disputing that. All I am saying is that it is not as easy as saying ##1+1 \neq 1##.
     
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