1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Photon Isospin

  1. Feb 26, 2004 #1
    I'm curious about the isospin of a photon. I have been told it is a linear combination of I=1 and I=0. If I=0, then I3 must be 0, but if I=1, what values of I3 are allowed?

    I don't really have a good idea of how to think about the isospin of this boson because I can't break it down into quarks like I can for pions.

    Any clarifications are appreciated.
     
  2. jcsd
  3. Feb 26, 2004 #2
    For I = 1, the allowed values of the isospin projection I3 are -1,0,1.
     
  4. Feb 26, 2004 #3

    arivero

    User Avatar
    Gold Member

    bkfizz02 probably your informant was thinking from the point of view of electroweak theory. There you have four particles, W+ W- Z and photon. It is obvious that W+ and W- change isospin, and one could think that Z is the 0 projection of the I=1 triplet. It is not; because such projection combines with the I=0 singlet to give both the Z and the photon. The mixing angle is called Weinberg angle.

    In any case it is very rare to think of electroweak bosons in this way.
     
    Last edited: Feb 26, 2004
  5. Feb 26, 2004 #4
    xeguy: Thanks, I guess I should have been more specific. I was curious what the specfic I3 value(s) is for the photon if it has I=1 because there are other exchange bosons that probably help span the spin 1 isospin space.

    arivero:
    Ok, this makes sense. I think I have heard it postulated that there exist to different particles (W0 and B0) which are the isospin states |1,0> and |0,0> respectively, but they are for book keeping and not observables. The observables are the Z and photon which are the usual linear combinations for the I3=0 states.

    So, I think that I can think of the photon as a linear combination of |1,0> and |0,0> in isopsin space. My main motivation is for figuring out allowable isospin channels for a wide range of scattering problems, so this has given me a good starting point.


    Thanks both for getting my thinking back on track.

    Cheers.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Photon Isospin
  1. Isospin question (Replies: 6)

  2. Isospin question (Replies: 3)

  3. Isospin asymmetry (Replies: 1)

  4. Decomposed isospin (Replies: 9)

Loading...