# Photon spin ?

1. Jun 30, 2010

### cragar

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. Jul 1, 2010

### haushofer

"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 :)

3. Jul 1, 2010

### cragar

thanks for the response , so the photons polarization depends on its spin projection ,