Orbital magnetic dipole moment of a proton

[abdossamad2003]

hi every one
what is the amount of orbital magnetic dipole moment of proton? this different with the intrinsic magnetic.

 

[BvU]

What orbit would that be ?

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[vanhees71]

That's in fact a question under vigorous study, and it's very hard to answer. The issue is that the proton is a very complicated bound state of quarks and gluons. A rough model is the "parton model" where it's considered as the bound state of three valence quarks, and this view is historically based on the phenomenology of deep-inelastic electron scattering and the corresponding Bjorken scaling. Today the view has become more complicated, where the proton is described by rather abstract parton distribution functions, where you do not only have three valence quarks somehow bound together in mind but also a "sea" of virtual quarks and gluons and you now ask, how the "bulk properties" of the progon(spin 1/2, the magnetic moment, the mass, charge, etc) is "made up of its constituents". The total spin 1/2 is in this view somehow made up from "orbital and spin angular momentum" of quarks and gluons with the further theoretical problem that in relativistic QFT it's hard to separate spin and angular momentum of elementary particles to begin with, particularly in gauge theories. What's in fact meant by this "split in contributions" are rather abstract "generalized parton-distribution functions".