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LZ Detector May Have Glimpsed a Dark Matter Particle — Just One Event, Not Proof
A new analysis of the LUX-ZEPLIN detector's data turned up one particle interaction consistent with dark matter, but at just 2.6-sigma statistical significance, physicists say it is far too soon to call it a discovery.
In June 2023, a new analysis of data from the LUX-ZEPLIN detector, known as LZ, found a single particle interaction that is consistent with dark matter, researchers reported September 1 at the TeV Particle Astrophysics meeting in Tendo, Japan, and in a paper posted on LZ's website. Physicists caution that one event alone is not conclusive proof of anything.
Dark matter is an invisible substance that has never been directly observed; its existence is inferred only from its gravitational pull on the universe. LZ, housed at the Sanford Underground Research Facility in Lead, S.D., hunts for a hypothesized form of dark matter called WIMPs (weakly interacting massive particles) by watching for them striking atomic nuclei inside a tank of liquid xenon. A strike produces a flash of light and releases electrons that the detector's sensors pick up.
After sifting through 220 days of data, "we got left with one event, which is fascinating — absolutely fascinating," said LZ spokesperson Rick Gaitskell, a physicist at Brown University. Physicists estimate there is only about a 1 in 100 chance that known particles, rather than dark matter, produced the signal — a statistical significance of 2.6 . Physics typically requires 3 sigma to claim evidence and 5 sigma to claim a detection.
Reactions were mixed. "It's the most interesting thing that's come up in recent times," said theoretical physicist Wick Haxton of the University of California, Berkeley, who was not involved in the work. Theoretical physicist Dan Hooper of the University of Wisconsin–Madison was more guarded: "It's only one event. So who knows what's really going on here... That said, it's intriguing." Dark matter searches have raised false hopes before, including a 2020 XENON1T signal later ruled out by its successor experiment.
LZ has already collected additional data beyond what was analyzed in this study — at least three times as much as the researchers have already examined.
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The story so far
- Suitcase-Sized Satellite Would Hide Behind the Moon to Hear a Signal From Before the First Stars
- Ghostly Star Stream Beyond the Milky Way Reveals Hidden Dark Matter
- Largest-Ever Test of Gravity Confirms Newton's Law Still Holds, Strengthens Case for Dark Matter
- Physicists Hunted a Known Particle at Jefferson Lab, Found Two Unexpected Structures Instead
- Chance Glance at Old Hubble Image Reveals Rare Stellar Stream That May Reveal Dark Matter's Secrets
- Ancient 'Dark Stars' May Explain a Mysterious Hum in Spacetime
- LZ Detector May Have Glimpsed a Dark Matter Particle — Just One Event, Not Proof
#dark matter#LUX-ZEPLIN#LZ experiment#WIMP#particle physics#Sanford Underground Research Facility
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