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,
aµ = 116592020 × 10-11
± (150 × 10-11).
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
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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