New Data Boosts Case for Higgs Boson Find
Physicists said that, based on a review of new data, they are confident that they have discovered a Higgs boson, a long-sought particle crucial to explaining the universe.
The Higgs boson is important because it is linked to a mechanism that confers mass to elementary particles—helping to explain the presence of stars, planets and all living things.
In July, the European particle-physics laboratory CERN, which runs an atom-smashing machine called the Large Hadron Collider, said it may have discovered a Higgs-like particle. Physicists have now analyzed 2½ times the amount of the original data from CERN experiments. The latest findings were reported Thursday at a physics conference in Italy.
The latest data "are magnificent and to me and it is clear that we are dealing with a Higgs boson though we still have a long way to go to know what kind of Higgs boson it is," Joe Incandela, a CERN spokesman, said in a news release.
This image provided by CERN shows a real CMS proton-proton collision in which four high energy electrons, the green lines and red towers, are observed in a 2011 event.
The Higgs boson is the only particle theorized by the standard model of physics that hasn't been conclusively observed in an experiment. The model describes how matter is built and how particles interact.
Particles like the Higgs have to be found indirectly, by hurtling them to near-light speed and then smashing them together to generate other subatomic entities. An analysis of these smash-ups indicates the mass of the particle being sought.
Since the initial findings were disclosed in the summer, physicists have eagerly awaited fresh experimental data.
The view back then "was like seeing a person in a fog—you knew there was a person there but you weren't sure who it was," said Andy Parker, a professor of high energy physics at the University of Cambridge who is involved in the CERN experiments. Thanks to the latest data, "we're no longer going to call it a Higgs-like boson but a Higgs boson."
Researchers must now pin down other properties of the particle.
All particles rotate and have spin—except for the Higgs, which is theorized to have a spin of zero. While initial number-crunching at CERN suggests the new particle has spin zero, more proof is needed.
"We've never seen an elementary particle with spin zero," said Tony Weidberg, a particle physicist at the University of Oxford who is also involved in the CERN experiments. "It's the beginning of a new chapter in physics."
Researchers are also studying the particle's parity—what its mirror-image looks like. A red ball looks exactly the same in a mirror and is said to have positive parity. A ball half red and half blue appears flipped over and has negative parity.
The standard model predicts that the Higgs will have positive parity; CERN's initial data suggests that is true for the new particle.
However, if the new particle doesn't have positive parity, then things get a lot more interesting—at least from a physicist's point of view.
It would mean that there is more than one type of Higgs boson; that the 50-year-old standard model would have to be thrown out; and that an alternative explanation—such as one called supersymmetry—might be needed instead.
Under supersymmetry, every particle has a heavier superpartner. Many scientists are betting on this theory to explain some big cosmic puzzles, such as dark matter.
Cosmologists reckon that at least a quarter of the universe is composed of dark matter, a mysterious substance that neither emits nor absorbs light. But they believe it is there because of the gravitational pull it exerts.
Under supersymmetry, dark matter could be made up of fermions, which are superpartners of bosons. "That could be an explanation for dark matter,' said Dr. Weidberg.
