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A Question about Spin Induced Magnetic Moment

  1. Sep 13, 2012 #1
    Does photon has spin induced magnetic moment? I think the answer is no. But why? You know, electron has. Does this have something to do with the fact that electron is massive while photon massless?:confused:
  2. jcsd
  3. Sep 13, 2012 #2


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    Primarily, it's because the electron is a charged particle and the photon is not.
  4. Sep 14, 2012 #3
    Some guy says it has something to do with photon's charge conjugation quantum number. If you have two photons' wave function [tex]\Psi_{p,\sigma}, \Psi_{p',\sigma'}[/tex], you can couple them to a electromagnetic current to measure the interaction and magnetic moment:


    But RHS has charge conjugation number +1 while LHS has charge conjugation number -1. So it's zero!

    I couldn't understand charge conjugation quantum number, though this theory sounds fancy.
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