Physics Colloquium - The Dance of the Muon
More than eighty years after the muon was discovered it is still a source of mystery. Indeed, experiments are underway that use muons as a window to search for new particles or forces. The muon's anomalous magnetic moment is a particular focus of these efforts because of a longstanding tension between experiment and theoretical expectations. This quantity is now known with an exquisite precision of 190 parts per billion, thanks to the g-2 experiment at Fermilab, which is on track to reach its precision goal of 120 part per billion in the next couple of years. The theoretical calculations of the muon's magnetic moment must account for the virtual effects of all particles and forces within the Standard Model, where effects coming from hadrons, governed by the strong interactions, are by far the largest sources of theory uncertainty. Recent estimates of hadronic corrections have created puzzles on the theory side, which are currently being investigated. I will discuss the ongoing interplay between theory and experiment that is essential to unlocking the discovery potential of this effort.