LZ detector records one unexplained event: a hint of dark matter or a statistical fluke

The LUX-ZEPLIN (LZ) experiment, the world's most sensitive dark matter detector, has recorded one interaction it cannot explain with known background processes, Brown University, one of the project's leaders, said on September 1.

The event turned up in 220 live days of data from a tank holding 10 tons of liquid xenon, nearly a mile underground in South Dakota. Its statistical significance is 2.6 sigma, about a 0.5 percent chance that it is background. Physics requires five sigma to claim a discovery.

Caution first

"With only one event, we don't want to get ahead of ourselves," collaboration spokesperson Rick Gaitskell said. If it is dark matter, the particle would weigh at least 200 GeV, about 200 times the mass of a proton.