Why do neutrinos have left-handed polarization if they oscillate?

[wotanub]

I was reading in my QM book that neutrinos are "essentially left handedly polarized." (Townsend on Page 119)

If neutrinos can be polarized, what is oscillating? Do other particles with mass exhibit polarization?

 

[Meir Achuz]

Yes. You don't need oscillation to get polarization. Particles can have intrinsic angular momentum, called spin.

 

[wotanub]

I'm not sure I understand completely.

What's the connection between spin of a photon and the polarization of the E field? Photons are spin 1 (3 eigenstates) and E polarization is a two state problem. I can't think of an obvious correspondence.

 

[jtbell]

Massive spin-1 particles have left-handed, right-handed and longitudinal polarization states. Massless ones like photons have only the left-handed and right-handed states, which are the two varieties of circular polarization.

 

[wotanub]

Is there a good reason spin-0 states are forbidden for massless particles? What's the underlying principle?

 

[Pseudo Epsilon]

maybe because without mass they need something to keep them existing?

 

[andrien]

well,the good reason is rather difficult to understand.the answer can be given in part on basis of lorentz invariance.see here page 87 and after
http://books.google.co.in/books?id=aQc5AAAAIAAJ&pg=PA87&dq=massless+particles+helicity&hl=en&sa=X&ei=whGBUf-eKMPtrQeXt4DIDw&ved=0CDcQuwUwAQ#v=onepage&q=massless%20particles%20helicity&f=false