New Results from the Muon g ‐ 2 Experiment

The Muon g ‐ 2 collaboration has measured the anomalous magnetic g value, a = (g ‐ 2)/2, of the positive muon with an unprecedented uncertainty of 0.7 parts per million. The result aμ+(expt) = 11659204(7)(5) × 10−10, based on data collected in the year 2000 at Brookhaven National Laboratory, is in good agreement with the preceeding data on aμ+ and aμ−. The measurement tests standard model theory, which at the level of the current experimental uncertainty involves quantum electrodynamics, quantum chromodynamics, and electroweak interaction in a significant way.