LOOKING INSIDE!

Charge distributions in nuclei, experiment and theory.


Neutron distributions are harder to measure because of absorption of the probe!




THE NUCLEON!

Here x = -q2/(2mp(E - E')). See sections 6.8, 6.9 in the text.  Physically, x is the fraction of the proton's total momentum carried by the particular particle that interacted with the electron.





An unfolding puzzle... where does the “spin” of the proton and neutron come from? It contains “orbital” contributions, and spin contributions from gluons, and from virtual pairs! More details here.


Calculation of electron |g|. One of the great triumphs of physics!
Calculation of g for the muon has proven far more difficult, because of its much more complex couplings to the vacuum.


Every calculation of the muon magnetic moment based on standard field-theoretic techniques, done up to date, shows a consistent discrepancy between experiment (as of August 2023) and theory. No satisfying explanation was at first evident, which suggested to many that new physics beyond the Standard Model might possibly be involved. However, the latest calculations using the lattice gauge theoretic approach are currently giving good agreement with the latest data. The field-theoretic calculations are so difficult, and involve so many semi-empirical estimates, that the discrepancies are generally not taken seriously.





Check this Comment.  And what about the electron??

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