# Different values of g factor (gyromagnetic ratio) of nuclei

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1. Nov 20, 2014

### mimocs

Hi, last week I read Rabi's paper "The Molcular Beam Resonance Method".
This paper contains the basic idea of the oscillation which we call "Rabi Oscillation" as many of you guys know.
However, at the end of this paper, Rabi calculates nuclear magnetic moments of Li (atomic mass 6), Li (atomic mass 7), F (atomic mass 19) by measuring the g factor of the atoms above.
Here's my Question.
g factor for Li (atomic mass 6) is 0.820,
Li (atomic mass 7) is 2.167
F (atomic mass 19) is 5.243
These values differ greatly. Are there any logical reasons to explain the differences of g factor?
Or is it just an intrinsic property of each atoms (just like the spin of electron is 1/2)?
Have a nice day

2. Nov 21, 2014

### UVCatastrophe

In principle, one can derive all of these results from QCD, the fundamental theory of strong interactions.

In principle, theory and practice are the same. In practice, they're different.

The only way predictions about hadrons and nuclei from QCD is by numerically simulating it on a lattice (lattice QCD). After nearly half a century, the state-of-the-art is finally yielding sensible result. I refer you here: http://arxiv.org/abs/1001.1131 **

It also depends on what you mean by "logical reasons." Lattice QCD seems to be in agreement with phenomenology...it's comforting to know it works, but is it satisfying? Depends on who you ask.

Suppose we have a computer that we tell about QCD and then ask it to spit out answers, e.g. about the spectrum of hadrons. The computer gives results that we extrapolate to the physical world and we find that the computer was right (its results are in agreement with the spectrum we observe in nature). Have we understood anything?

***the paper has also been published in Phys. Rev. D81 054502 (2010) )