text: The QED one-loop correction to the electron's value for this quantity equals the fine structure constant divided by 2 pi.
full_question: The QED one-loop correction to the electron's value for this quantity equals the fine structure constant divided by 2 pi. QCD predicts that the ratio of this quantity for the proton to this quantity for the neutron equals minus three halves. For an electron, QED predicts this quantity's classical version to be multiplied by a factor of 2.002, an improvement in accuracy over the factor of 2 predicted by the Dirac equation. Along with the flux and the longitudinal invariant, this quantity is the first adiabatic invariant for a gyrating charged particle. This value for an object divided by an object's angular momentum gives the gyromagnetic ratio, and that aforementioned factor of 2.002 which multiplies this quantity's classical version in quantum mechanics is the g-factor. The electron's value for this quantity is a physical constant named for Bohr. For 10 points, name this quantity equal to the product of the area of a current loop and the current going through the loop, which is symbolized mu, like its electric counterpart.
first_sentence: The QED one-loop correction to the electron's value for this quantity equals the fine structure constant divided by 2 pi.
raw_answer: magnetic dipole moment [prompt on "mu"]