Muon g-2

When theory and experiment disagree, it could mean new physics. With the recent announcement of the most precise measurement of the magnetic moment of the muon, the anomaly is no more.

Muon g-2 collaborator describes the latest precision of the muon measurement to an an 11,000-pound elephant standing on a bathroom scale. The scale is so precise, it can measure if a couple of sunflower seeds are placed on the elephant’s back.

Final results from the Fermilab Muon g-2 experiment was announced on June 3, showing a tiny particle continues to act strangely — but that’s still good news for the laws of physics as we know them.

The deviant behavior of a tiny particle called the muon might point to undiscovered forms of matter and energy in the universe. Or it might not.

The third and final result, based on the last three years of data, is in perfect agreement with the experiment’s previous results, further solidifying the experimental world average. This long-awaited value will be the world’s most precise measurement of the muon magnetic anomaly for many years to come.

A Fermilab-led computing project received the second-largest award and was the largest particle physics project granted supercomputer time from the DOE Office of Science INCITE program. The project will continue to further explore numerical simulations to address questions in particle physics.

The Cern Courier explores the experimental results and theoretical calculations used to predict ‘muon g-2’ – one of particle physics’ most precisely known quantities and the subject of a fast-evolving anomaly.

In recent years, a new SM prediction of the muon g-2 has emerged that questions whether the discrepancy exists at all, suggesting that there is no new physics in the muon. Alex Keshavarzi, a member of the Muon g-2 Experiment and the Muon g-2 Theory Initiative, discusses what is next for the final result for g-2 in 2025.

In the quest to understand the fundamental forces that govern our universe, the Standard Model of particle physics has long stood as the cornerstone. Recent experimental discrepancies like those from Fermilab’s Muon g-2 experiment, have stirred the physics community, suggesting that the muon’s behavior under magnetic fields might not fully align with Standard Model prediction.

Brynn Kristen MacCoy’s work on improving beam dynamics has helped Muon g-2 researchers better understand and account for the behavior of the muon beam.