The experimental value of the muon’s magnetic moment disagrees with theoretical predictions, but some of those predictions also disagree with each other a problem theorists are working to resolve.
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Muons, particles akin to electrons, have kepts physicists heads spinning for more than a decade, because an experimental measurement of their magnetic properties (1) disagrees with theory. Could this be caused by unknown particles or forces?
A new theoretical calculation of this parameter, involving CNRS physicists and published in the journal Nature, has reduced the discrepancy with the experimental measurement. The debate nevertheless continues.
For over 10 years, measurement of the magnetic properties of the muon (an ephemeral cousin of the electron) has exhibited disagreement with theoretical predictions. This suggests a possible gap in the standard model of particle physics (2), possibly providing a glimpse of a more exotic physics. The first results of Fermilab s Muon g-2 experiment, which measures one of these properties known as the muon magnetic moment, will be revealed on 7 April 2021.