How large is the "natural" magnetic moment?
This is the pre-published version which is collected from arXiv. The published version is at http://ajp.aapt.org/resource/1/ajpias/v74/i12/p1104_s1
The “natural” magnetic moment of a particle of spin S is generally assumed to be that given by the Belinfante conjecture and has the gyromagnetic ratio g=1∕S. Thus, for the spin 1∕2 electron we find the Dirac value ge=2. However, in the standard model the charged W-boson, a spin-one particle, is found to have gW+=2. We discuss this result and argue that the natural value for any particle of spin S should be g=2, independent of spin.
BR Holstein. "How large is the "natural" magnetic moment?" American Journal of Physics 74.12 (2006): 1104-1111.
Available at: http://works.bepress.com/barry_holstein/44