Brainy Quote of the Day

Monday, February 5, 2018

Muon Magnetic Moment...

The g-2 magnet arrives at Fermilab to be installed in the Muon g-2 experiment (Courtesy: Fermilab)

Topics: Modern Physics, Particle Physics, Quantum Mechanics

Physicists in Japan say they have a solution to a problem that has puzzled particle physicists for nearly two decades – the anomalous magnetic moment of the muon.

Measurements made over several years at the at the g-2 experiment at the US’s Brookhaven National Laboratory suggest that the muon magnetic moment is significantly larger than predicted by the Standard Model of particle physics. After careful analysis of data related to the decay of the muon to an electron, the statistical significance of this discrepancy is at 3.6σ – which means that it is extremely unlikely to be a fluke.

One possible explanation is that particles not described by the Standard Model are involved in the muon decay, and their presence affects the measured value of the muon magnetic moment. Finding evidence for such particles would be a colossal achievement, which is why the new Muon g-2 experiment at Fermilab is gathering data this year.

Now, however, Takahiro Morishima of Nagoya University and Toshifumi Futamase of Kyoto Sangyo University have come up with an alternative explanation of the anomaly. In three preprints uploaded to the arXiv server, the duo calculate that effects due the curvature of space-time could result in an increase in the measured value of the magnetic moment. This effect of general relativity is related to the gravitational field of the Earth.

Has the muon magnetic moment mystery been solved? Hamish Johnston, Physics World

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