“Wonderful, beautiful and unique” is how Gordon Kane describes supersymmetry theory. Kane, a theoretical physicist at the University of Michigan in Ann Arbor, has spent about 30 years working on supersymmetry, a theory that he and many others believe solves a host of problems with our understanding of the subatomic world. Yet there is growing anxiety that the theory, however elegant it might be, is wrong. Data from the Large Hadron Collider (LHC), a 27-kilometre proton smasher that straddles the French–Swiss border near Geneva, Switzerland, have shown no sign of the 'super particles' that the theory predicts1–3. “We're painting supersymmetry into a corner,” says Chris Lester, a particle physicist at the University of Cambridge, UK, who works with the LHC's ATLAS detector. Along with the LHC's Compact Muon Solenoid experiment, ATLAS has spent the past year hunting for super particles, and is now set to gather more data when the LHC begins a high-power run in the next few weeks. If the detectors fail to find any super particles by the end of the year, the theory could be in serious trouble.
Supersymmetry (known as SUSY and pronounced 'Susie') emerged in the 1970s as a way to solve a major shortcoming of the standard model of particle physics, which describes the behaviour of the fundamental particles that make up normal matter (see 'The bestiary'). Researchers have now found every particle predicted by the model, save one: the Higgs boson, theorized to help endow other particles with mass.