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Fermilab scientists discover new four-flavor particle  

Scientists on the DZero collaboration at the U.S. Department of Energy's Fermilab have discovered a new particle - the latest member to be added to the exotic species of particle known as tetraquarks. As is the case with many discoveries, the tetraquark observation came as a surprise when DZero scientists first saw hints in July, 2015 of the new particle, called X(5568), named for its mass-5568 megaelectronvolts.

"At first, we didn't believe it was a new particle," says DZero co-spokesperson Dmitri Denisov." Only after we performed multiple cross-checks did we start to believe that the signal we saw could not be explained by backgrounds or known processes, but was evidence of a new particle."

"The next question will be to understand how the four quarks are put together," says DZero co-spokesperson Paul Grannis. "They could all be scrunched together in one tight ball, or they might be one pair of tightly bound quarks that revolves at some distance from the other pair." Four-quark states are rare, and although there's nothing in nature that forbids the formation of a tetraquark, scientists don't understand them nearly as well as they do two- and three-quark states.

The Stony Brook faculty from the Department of Physics and Astronomy’s High Energy Physics Group include Distinguished Research Professor Paul Grannis, Professor John Hobbs, Associate Professor Dmitri Tsybychev, Professor Robert McCarthy and Research Professor Dean Schamberger. They participated in the DZero project from its inception and co-authored the paper.

See more here and here.

2016-02-25

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