In December, scientists at CERN moved closer to nabbing the Higgs, the particle that is thought to explain what gives everything mass. Or to not finding it at all. In his latest video update, Fermilab scientist Don Lincoln fills us in and shows how the Large Hadron Collider (and until November, Fermilab’s Tevatron) searches for the Higgs in the debris of massive particle collisions.
This is how it works: according to the Standard Model of physics, if the Higgs’ mass is 100 times the mass of a proton, it is most likely to decay into bottom quarks. But at higher masses, the Higgs would be more likely to decay into W bosons. At still higher masses, it would decay into top quarks. “The difficulty is to catch as many events corresponding to the decay of a Higgs boson while rejecting the what we call the background,” Pauline Gagnon, a CERN physicist, blogged in December. “It is as if we want to take a photo of a small flash of light in bright daylight.”
“Events coming from the background will not have a particular mass,” she continues, “but if the decay products all come from the same particle, a Higgs boson for instance, they will start clustering in one spot. And that would be the clear sign that we have found it.”
Researchers have already ruled out many possible masses already, so the focus now is on the range of 126 GeV. If the Higgs isn’t there — and we are likely to know sometime soon — then our model of physics may need rewriting. Which would be, um, interesting.
Until then, Fermilab has made even an interactive version of that graphic, so you can play particle physicist, for a few microseconds at least. Note please that the actual top quark does not wear a top hat.
Move your mouse across the mass spectrum at the top of the graphic to see into what particles the Higgs is likely to decay.