Photon spin ?

  1. My teacher said in class a while back that a photon can have a spin of -1 , 0 , 1 ,
    Is this correct , And also it says on Wikipedia that photons and gluons and W and Z bosons can have 3 different possibilities for their spin angular momentum , obviously Wikipedia could be wrong
    http://en.wikipedia.org/wiki/Stern–Gerlach_experiment
    if you look in the Basic theory and description section on the wiki article about 80% the way down it had photons and W and Z bosons highlighted in blue and talks about their spin ,
    I have not studied QM very much ,
     
  2. jcsd
  3. haushofer

    haushofer 990
    Science Advisor

    Your teacher is wrong :)

    "Spin" s is an intrinsic property of a particle and has one value: 0,1/2,1,... However, the spin can be projected. For massive particles this gives 2s+1 different projections. For a spin-1 particle this is thus 2s+1=2+1=3 different projections. However, the caveat here is ofcourse that photons are massless. Mathematically this erases one of the projections (degrees of freedom), and thus the photon has 2 projections. This corresponds to the experimental well-known fact that photons have 2 different polarizations.

    For your W and Z bosons; these are massive, and as such do have 2s+1=3 polarizations.

    Hope this helps :)
     
  4. thanks for the response , so the photons polarization depends on its spin projection ,
     
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