By Ron Cowen, Science News April 4, 2011
The Large Hadron Collider, the world’s most powerful atom smasher, may be only months away from finding a new elementary particle — a sign of a new force in nature — recent studies suggest.
The studies focus on the top quark, the heaviest of the six quarks, which are the fundamental building blocks of nature. Top quarks appear to behave badly when they are produced during proton-antiproton collisions at a lower-energy particle accelerator, the Fermilab’s Tevatron in Batavia, Illinois.
Compared with what the standard model of particle physics predicts, these quarks fly off too often in the direction of the proton beam and not enough in the antiproton direction.
The Tevatron finding was first reported in 2008, but the results could have been due to chance. A recent report, using additional data, boosts confidence in the result, says Dan Amidei of the University of Michigan in Ann Arbor, a member of the Tevatron’s CDF experiment. For energies above 450 billion electron volts, 45 percent of the top quarks travel along the path of the proton beam, while only 9 percent are expected to do so, Amidei and colleagues reported online January 3 at arXiv.org. The team reported additional evidence online March 10 of the top quark’s puzzling directional preference, after examining the paths of quarks generated by a different set of particle interactions.
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