There’s a new measurement of muon magnetism. What it means isn’t clear

The measurement is the most precise yet, but theoretical predictions are muddled

A photo of the doughnut-shaped magnet that was used with the Muon g-2 experiment.

Physicists with the Muon g−2 experiment studied how muons wobbled as they circulated within a doughnut-shaped magnet (pictured) and made the most precise measurement of a magnetic property of the particle.

Ryan Postel/Fermilab

Muons might not behave as expected. But scientists can’t agree on what to expect.

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