Physicists have found the strongest sign yet of a fabled four of a kind.
For six decades, researchers have hunted for clusters of four neutrons called tetraneutrons. But evidence for their existence has been shaky. Now, scientists say they have observed neutron clusters that appear to be tetraneutrons. The result strengthens the case that the fab four is more than a figment of physicists’ imaginations. But some scientists doubt that the claimed tetraneutrons are really what they seem.
Unlike an atomic nucleus, in which protons and neutrons are solidly bound together, the purported tetraneutrons seem to be quasi-bound, or resonant, states. That means that the clumps last only for fleeting instants — in this case, less than a billionth of a trillionth of a second, the researchers report in the June 23 Nature.
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