Single top quark in the palm of your hand
There's more than one way to find a single top quark.
You can spend more than a decade combing through data from a particle collider, as scientists in Fermilab's CDF and DZero collaborations did.
Or you can commission one from Julie Peasley, a soft sculpture artist in Los Angeles.
Fermilab recently announced the first observation of the single top quark, a top quark produced without an anti-top quark. Fermilab physicists discovered the top quark in 1995. Until recently, they had only observed top quarks in pairs with their antiparticles.
Physicist Heidi Schellman, a professor at Northwestern University who works with the DZero collaboration, ordered a plush toy version of the top quark from Particle Zoo in honor of the accomplishment.
Particles produced in collisions in the Tevatron, Fermilab's particle collider, quickly decay into other particles, which physicists use to identify the higher-energy particles from which they came. The single top quark decays into a bottom quark and a W boson, which in turn decays into an electron and a neutrino or a muon and a neutrino.
The decay of the single top quark is similar to the decay expected of a hypothetical charged Higgs boson. So the observation of the single top may represent, among other possibilities, a step toward the discovery of the Higgs.
Schellman contacted Julie Peasley, who sells plush toy versions of fundamental particles in the Standard Model, to commission a top quark that would decay. Peasley came up with the idea of making a top quark with a zipper that would hold two smaller plush toys, an antimuon and a neutrino. The top quark reverses into the third musketeer of the decay, a bottom quark.
Peasley has no background in science, but "this lady understands at a rather deep level how this works," Schellman said. Peasley started as a graphic designer.
"I've always been interested in theoretical physics since I was in high school, reading about the origin of the universe," she said. She rekindled that interest when she read Warped Passages, a nonfiction book by Lisa Randall, a Harvard professor of physics.
"Particles seemed to have personalities," Peasley said. "That tied in with my current interest in handmade crafts...The good thing about it is that I can have pretty high artistic license because nobody can tell me, ‘That's not what it looks like.'"
Schellman has commissioned custom particles before, including three oscillating neutrinos and a decaying strange bottom meson that unzips to reveal a strange quark, a bottom quark, and a gluon. She gave duplicates of the latter to students who graduated after studying strange bottom meson decay.
Schellman only commissioned one decaying top quark. "For now, there's only one," she said. "It's the single top quark."