Update on the Anomalous Magentic Moment of the Muon

In February 2001, newspapers around the world announced that a muon experiment at the Brookhaven National Laboratory had revealed a flaw in the Standard Model of Particle Physics. Jupiter Scientific Publishing criticized this reporting because it overemphasized the importance of the result. Now a paper has appeared that undermines the discrepancy between theory and the Brookhaven experiment that has measured the anomalous magnetic moment of the muon aµ.
     Measurements of leptonic magentic moments are among the most precisely made in particle physics. For the muon, Brookhaven obtains
aµ = 116592020 × 10-11 ± (150 × 10-11).
Brookhaven experimentalists compared this result to the theoretical prediction of
aµ = 116591597 × 10-11 ± (67 × 10-11)
and concluded that there is only a 1% chance that experiment agrees with theory.
     However, the Russian physicist Kirill Melnikov (currently at the Stanford Linear Accelerator Center) argues that the theoretical error in aµ is understated and he has redone some of the theoretical analysis. His work, which is available at a Los Alamos Archive, claims that the theoretical error is as large as ± 156 × 10-11. He obtains the following for the difference between experiment and theory:
377 × 10-11 ± (150 × 10-11) ± (156 × 10 -11).
If Dr. Melnikov's conclusions are true then, although there is still a discrepancy between theory and experiment, the difference is not sufficiently large to be newsworthy.

To the Original Report on the Anomalous Magnetic Moment of the Muon
To the Jupiter Scientific's Science Information Page

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