Physicists think they've solved the muon mystery

Researchers combined lattice QCD supercomputer simulations with experimental inputs to compute the muon’s magnetic properties with record precision.

The result shows muon g-2 agrees with the Standard Model to within about half a standard deviation, sharply reducing earlier tension.

By pinning down the strong-force contribution more precisely, the work tightens the muon magnetic moment calculation.

That leaves less room for new physics, including ideas for a possible fifth force.