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Photon-Photon Scattering

  1. Dec 23, 2015 #1
    Why do particles scatter in particle-particle collision while photons don't in photon-photon collisions, assuming that photons don't have enough energy to create particle anti-particle pairs?
  2. jcsd
  3. Dec 23, 2015 #2


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    What force would do the scattering ?
  4. Dec 23, 2015 #3
    ie.. they have no mass
  5. Dec 23, 2015 #4


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    Photons can in fact scatter off each other "indirectly", via intermediate virtual electron-positron pairs. See e.g. page 4 (problem 3) of this document:


    The cross-section (i.e. the probability) is very small because the Feynman diagram has four vertices as opposed to only two in electron-electron scattering.
  6. Dec 23, 2015 #5
    I have very little knowledge of QED, but can you tell me what dictates exchange of bosons (particle-particle interaction) or electrons (in case of photon-photon interaction) in scattering processes? It will be helpful if you provide some links to further illustrate the point.
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