The LUX-ZEPLIN experiment has reported a single unusual particle interaction that researchers say could be its strongest hint yet of a weakly interacting massive particle. The finding comes from data collected between March 2023 and April 2024, after the collaboration searched for a wider range of possible dark matter interactions.
Rick Gaitskell, the LZ spokesperson and a professor at Brown University, said, "We’re very intrigued to see this event in the data, in the region where we expect dark matter to show up and the competing backgrounds are very low."
Sam Eriksen and 220 days
The new analysis used 220 live days of data and focused on interactions that could deposit more energy in the detector than the simplest searches examined before. Sam Eriksen, a senior research associate at the University of Bristol and the study’s lead author, said, "This was a detailed study in a region we hadn’t explored within this dataset, and we spent months of additional effort to understand all the possible causes of background events."
He added, "We understand our detector and the backgrounds so well that even a single outstanding event, like the one we found, is important." The team said dark matter events are expected to be extremely rare, and Eriksen said, "We expect dark matter events to be extremely rare, so only a handful could mark the first detection of WIMP dark matter."
Sanford Underground Research Facility
The detector sits nearly one mile below ground at the Sanford Underground Research Facility in South Dakota and uses 10 tonnes of ultrapure liquid xenon to look for WIMPs, or weakly interacting massive particles. DOE's Lawrence Berkeley National Laboratory manages the experiment, which is run by an international collaboration of 250 scientists and engineers from 39 institutions.
That underground setting and the xenon target are built to cut down false positives while the team searches for extremely rare signals. If the anomalous event came from dark matter, the WIMP that produced it would likely have a mass of at least 200 GeV/c2, more than 200 times the mass of a proton.
2026 TeV Particle Astrophysics conference
The result was presented in a scientific talk at the 2026 TeV Particle Astrophysics conference in Japan. Gaitskell said, "With only one event, we don’t want to get ahead of ourselves. We are not claiming to have seen dark matter. But we have seen something interesting that we want to share with the scientific community for their input."
After the talk, the paper will be released on arXiv and submitted to Physical Review Letters, giving other researchers a chance to test whether the lone interaction fits a dark matter signal or a background explanation.
