Re: Do free particles have spin?

From: Igor (thoovler_at_excite.com)
Date: 09/26/04 

Date: 25 Sep 2004 23:46:54 -0700

David Rutherford <drutherford@softcom.net> wrote in message news:<ts-dnWN56rwlOcjcRVn-rg@softcom.net>...
> Paul Draper wrote:
>
> > David Rutherford <drutherford@softcom.net> wrote in message news:<w4mdnSYXV63XwsncRVn-pA@softcom.net>...
> >
> >>Is there any evidence for the existence of particle spin for free
> >>particles, that is, for particles not bound to atoms? If so, please give
> >>references or links.
> >>
> >>--
> >
> >
> > SLAC's collider has been firing polarized electrons at each other for some time now.
>
> Thanks Paul. From what I've read, at least for photons, polarization and
> spin are two different things. For photons, the spin axis is in the
> direction of travel and the polarization axis is perpendicular to the
> direction of travel. Is that also true for electrons?
>

I think you are confusing the polarization axis with the polarization
plane. They are perpendicular. Besides, spin can really only be
defined to be a good quantum number if it points in the direction of
motion (or opposite to it). This is required for commutation of
angular and linear momentum operators.

Relevant Pages

  • Re: Do free particles have spin?
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