Electron's shapeliness throws a curve at supersymmetry

A small band of particle-seeking scientists at Yale and Harvard has established a new benchmark for the electron's almost perfect roundness, raising doubts about certain theories that predict what lies beyond physics' reigning model of fundamental forces and particles, the Standard Model. "We know the Standard Model does not encompass everything," said Yale physicist David DeMille, who with John Doyle and Gerald Gabrielse of Harvard leads the ACME collaboration, a team using a strikingly different method to detect some of the same types of particles sought by huge experiments at the Large Hadron Collider (LHC) in Europe. "Like our LHC colleagues, we're trying to see something in the lab that's different from what the Standard Model predicts." ACME is looking for new particles of matter by measuring their effects on the shape of the electron, the negatively charged subatomic particle orbiting within every atom. In research published Dec. 19 in Science Express, the team reported the most precise measurement to date of the electron's shape, improving it by a factor of more than 10 and showing the particle to be rounder than predicted by some extensions of the Standard Model, including some versions of Supersymmetry. This theory posits new types of particles that help account, for example, for dark matter, a mysterious substance estimated to make up most of the universe. Researchers said they have shown that the electron's departure from spherical perfection - if it exists at all - must be smaller than predicted by many theories proposing particles the Standard Model doesn't account for.