Davide Castelvecchi in Nature:
Last year, an experiment suggested that the elementary particle had inexplicably strong magnetism, possibly breaking a decades-long streak of victories for the leading theory of particle physics, known as the standard model. Now, revised calculations by several groups suggest that the theory’s prediction of muon magnetism might not be too far away from the experimental measurements after all.
The new predictions are preliminary, and do not completely vindicate the standard model. But by narrowing the gap between theory and experiment, they might make it easier to resolve the discrepancy — while potentially creating another one.
More here.