Muon g-2

Muon g−2 is a particle physics experiment at Fermilab to measure the anomalous magnetic dipole moment of a muon to a precision of 0.14 ppm, which will be a sensitive test of the Standard Model. It might also provide evidence of the existence of entirely new particles. The muon, like its lighter sibling the electron, acts like a spinning magnet. The parameter known as the "g-factor" indicates how strong the magnet is and the rate of its gyration. The value of g is slightly larger than 2, hence the name of the experiment. This difference from 2 is caused by higher-order contributions from quantum field theory. In measuring g−2 with high precision and comparing its value to the theoretical prediction, physicists will discover whether the experiment agrees with theory. Any deviation would point to as yet undiscovered subatomic particles that exist in nature. The three data-taking periods have been completed, with preparations for Run-4 currently ongoing.