Muon's magnetism could point to new physics

Next week, physicists will pick up an old quest for new physics. A team of 190 researchers at Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois, will begin measuring the magnetism of a fleeting particle called the muon to exquisite precision, in an experiment known as Muon g-2 (pronounced "gee minus two"). They hope to firm up tantalizing hints from an earlier incarnation of the experiment that suggested that the particle is ever so slightly more magnetic than predicted by the prevailing standard model of particle physics. That would give researchers something they have desired for decades: proof of physics beyond the standard model. From 1997 to 2001, researchers on the original g-2 experiment at Brookhaven National Laboratory in Upton, New York, saw tantalizing, but inconclusive signs of an excess in the muon magnetism. In 2013, the team lugged the experiment to Fermilab, taking the 28-meter-wide ring by barge around the U.S. eastern seaboard and up the Mississippi River. Now, they have rebuilt, and over the next 3 years they hope to push it to its limits—and perhaps a thrilling new discovery.