The Resolution of the
At the beginnin of last year (2001), Brookhaven National Laboratory announced that it
had revealed a flaw in the Standard Model of Particle Physics. The lab had measured
the anomalous magnetic moment of the muon and found its value to disagree with theory. In its
original report, Jupiter
Scientific criticized the way newspapers had reported the result because they overemphasized
Anomalous Magentic Moment Result of the Muon
The discrepancy has now been resolved. It turns out that
theorists had made a mistake in their calculations. The sign
of a contribution coming from the pion, known as the pion pole term, was incorrect. The pion
is a short-lived subnuclear particle made from a u or d quark and an anti- u or d quark. Such
quark anti-quark bound states are known as mesons, of which the pion is the lightest weighing
about 1/6th the mass of a proton. On April 5, 2002, Physical Review D
published the work of Marc Knecht and Andreas Nyffeler revealing the sign error.
After correcting the theoretical value, one finds that experiment and theory are in agreement. Case closed!
To the Original Report on the Anomalous Magnetic Moment
of the Muon
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