Dreams of new physics fade with latest muon magnetism result

The most precise measurement of an elementary particle’s magnetism suggests that the ‘standard model’ of physics could be right after all. A discrepancy between predicted and measured values of the magnetic moment of the muon — a heavier cousin of the electron — was seen as a possible signal of undiscovered subatomic particles. Physicists at the Muon g – 2 experiment at Fermilab have now doubled the precision of the previous best measurement, to an estimated error of just 201 parts per billion. And an alternative theoretical prediction is in agreement with this result, suggesting there might not be any discrepancy to explain.