The most massive subatomic cousins of protons and neutrons ever detected have made fleeting appearances in a U.S. particle accelerator.
The weightiest parts of the particles—known as sigma-b baryons—are called bottom quarks, one of the six types of quarks that are fundamental constituents of matter.
Physicists at Fermi National Accelerator Laboratory in Batavia, Ill., announced the exotic particles' discovery at the lab on Oct. 23. The scientists found telltale traces of the sigma-bs in the debris produced by more than 100 trillion collisions of protons and antiprotons that had occurred in the accelerator in the past 5 years.
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