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It looks like the Large Hadron Collider (LHC) may have some competition in its search for the much-anticipated Higgs boson, the source of mass.
Yesterday CERN, the European particle physics lab, announced that on September 10 it would begin shooting protons around the full 27 kilometers (17 miles) of the circular LHC—the most powerful particle accelerator ever built—building up to collisions with a second, opposing beam in subsequent months.
Researchers don't know much concentrated energy it takes to make the Higgs particle pop out, but they are confident that the sheer number of high-energy particle collisions the LHC was designed to produce ought to generate lots of Higgs bosons, enough to spot them from among other collision debris.
But the LHC isn't the only machine with the potential for finding the Higgs. At a conference this week, researchers working on the Tevatron [above, background] at Fermi National Accelerator Laboratory (Fermilab) in Batavia, Ill.—still the top particle accelerator for a few months more—have finally collected enough data that they can start to rule out the Higgs along portions of the energy range the LHC will also explore.
Combined results from the CDF and DZero experiments indicate that the Higgs most likely does not exist at 170 giga electron-volts (GeV). (A GeV is one billion electron-volts, which are the units of energy associated with subatomic particles.)
Tevatron researchers have been hard at work these past months squeezing every bit of sensitivity from their data to identify enough Higgs-like particle collisions to see if there's an excess suggesting the possible presence of the Higgs.
The finding "marks the start of an expanding region both below and above 170 GeV where the Higgs will be excluded as we collect more statistics and refine our analysis," Fermilab director Pierre Oddone said in a statement. "Even more exciting, if the Higgs is anywhere nearby, we should then see evidence for it with the full data sample in the next two years."
Physicist Gordon Watts, a DZero team member, notes on his blog that this is the first time a particle physics experiment has entered the Higgs range since CERN's LEP collider in the 1990s, which told researchers that the Higgs had to possess an energy greater than 114 GeV.
The LHC will need a few years to complete its own Higgs hunt, as indicated in this provisional timeline, circulated at April's meeting of the American Physical Society. Of course, the machine will be looking for other particles besides the Higgs. Check out Cosmic Variance for a run-down of what's theoretically possible.
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Image credit: Fermilab, Reidar Hahn