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Onium, how can it exist?

  1. Oct 10, 2015 #1
    1. The problem statement, all variables and given/known data
    How can an onium exist? Since it is a particle with its own antiparticle, how can it even exist? Shouldn't the particle and the anti-particle annihilate each other?

    2. Relevant equations


    3. The attempt at a solution
     
  2. jcsd
  3. Oct 10, 2015 #2

    gneill

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    Staff: Mentor

    What does your research on the topic suggest? Have you found evidence of a stable onium?
     
  4. Oct 10, 2015 #3
    I've not been able to find any evidence for stable onium. But since it's an particle withit's own anti-particle it shouldn't be able to exist at all.
    When it comes to positronium, it's an elektron and a positron that circulates around a common center of mass. Is it the common center of mass that stops them from annihilating each other?
    And the pi-meson (π0) becomes a superposition. But how is it able to become a superposition instead of having the (for example) down-quark and the anti-downquark annihilation each other?
     
  5. Oct 10, 2015 #4

    gneill

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    Staff: Mentor

    I think you'll find that all -oniums have very short half lives. The charged pions in particular have a mean lifetime of about 26 nanoseconds, while the neutral pion's (##\pi^0##) is really short at about 8 x 10-17 seconds.

    So you might think of them as particles that are assembled and then live very briefly.
     
  6. Oct 10, 2015 #5
    I understand that have very short lifetimes. But how are they able to assemble at all? Or is -onium just an expression for the state just before a particle and it's antiparticle annihilate each other?
     
  7. Oct 10, 2015 #6

    gneill

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    Staff: Mentor

    Well, where/how are -oniums found? Maybe do a bit of research on their discoveries?
     
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