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Another q on electron positron collisons

  1. Jan 20, 2010 #1
    Another q on electron positron collisons :)

    I asked earlier about why spin-0 bottomonium mesons aren't created directly with electron positron collisions.
    So I found out that when an electron and positron collides, it may make a virtual photon, and the virtual photon turns into a spin-1 bottomonium meson.
    Trying to understand this, here's my guesses:

    Although a virtual particle can borrow energy and thus temporarily violate energy conservation, virtual particle creation & destruction has to obey spin conservation. So a virtual photon can only be converted into something with spin 1.
    And when the electron and positron collide, they'd have to have spin in the same direction, in order to annihilate into a virtual photon. Otherwise something else would happen.
    I noticed that if the electron and positron have spin in opposite directions, their magnetic moments would be in the same direction so there'd be a repulsion. I don't know if this is a significant effect here?
    So when you're trying to produce bottomonium mesons, would you try to make sure that the electron and positron have spin in the same direction?
  2. jcsd
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