  The New Muon $(g-2)$ Collaboration at Fermilab has proposed to measure the
anomalous magnetic moment of the muon, $a_\mu$, a factor of four better than
was done in E821 at the Brookhaven AGS, which obtained $a_\mu = [116 592 089
(63)] \times 10^{-11}$ $\pm 0.54$ ppm. The last digit of $a_{\mu}$ is changed
from the published value owing to a new value of the ratio of the
muon-to-proton magnetic moment that has become available. At present there
appears to be a difference between the Standard-Model value and the measured
value, at the $\simeq 3$ standard deviation level when electron-positron
annihilation data are used to determine the lowest-order hadronic piece of the
Standard Model contribution. The improved experiment, along with further
advances in the determination of the hadronic contribution, should clarify this
difference. Because of its ability to constrain the interpretation of
discoveries made at the LHC, the improved measurement will be of significant
value, whatever discoveries may come from the LHC.
