A New Measurement of the Muon Magnetic Anomaly

摘要

The muon magnetic anomaly may contain contributions from physics beyond thestandard model. At the Brookhaven National Laboratory (BNL) a precisionexperiment aims for a measurement of the muon magnetic anomaly $a_{\mu}$ to0.35 ppm, where conclusions about various theoretical approaches beyondstandard theory can be expected. The difference between the spin precession andcyclotron frequencies is measured in a magnetic storage ring with highlyhomogeneous field. Data taking is in progress and part of all recorded data hasbeen analyzed. Combining all experimental results to date yields preliminarily$a_{\mu}(expt)=1~165~921(5) \cdot 10^{-9}$ (4 ppm) in agreement with standardtheory.