The newest results from LUX-ZEPLIN (LZ) extend the experiment’s search for low-mass dark matter and set world-leading limits on one of the prime dark matter candidates: weakly interacting massive particles, or WIMPs. They also mark the first time LZ has picked up signals from neutrinos from the sun, a milestone in sensitivity.

LZ is an international collaboration of 250 scientists and engineers from 37 institutions, including Distinguished Professor Mani Tripathi at the UC Davis Department of Physics and Astronomy. The detector is managed by the Department of Energy’s Lawrence Berkeley National Laboratory and operates nearly one mile below ground at the Sanford Underground Research Facility (SURF) in South Dakota. 

The new results use the largest dataset ever collected by a dark matter detector and have unmatched sensitivity. The analysis, based on 417 live days of data that were taken from March 2023 to April 2025, found no sign of WIMPs with a mass between 3 GeV/c² (gigaelectronvolts/c²), roughly the mass of three protons, and 9 GeV/c². It’s the first time LZ researchers have looked for WIMPs below 9 GeV/c², and the world-leading results above 5 GeV/c² further narrow down possibilities of what dark matter might be and how it might interact with ordinary matter. The results were presented today (Dec. 8) in a scientific talk at SURF and will be released on the online repository arXiv. The paper will also be submitted to the journal Physical Review Letters. 

“We have been able to further increase the incredible sensitivity of the LUX-ZEPLIN detector with this new run and extended analysis,” said Rick Gaitskell, a professor at Brown University and the spokesperson for LZ. “While we don’t see any direct evidence of dark matter events at this time, our detector continues to perform well, and we will continue to push its sensitivity to explore new models of dark matter. As with so much of science, it can take many deliberate steps before you reach a discovery, and it’s remarkable to realize how far we’ve come. Our latest detector is over 3 million times more sensitive than the ones I used when I started working in this field.”

Dark matter has never been directly detected, but its gravitational influence shapes how galaxies form and stay together; without it, the universe as we know it wouldn’t exist. Because dark matter doesn’t emit, absorb, or reflect light, researchers have to find a different way to “see” it. 

LZ uses 10 tonnes of ultrapure, ultracold liquid xenon. If a WIMP hits a xenon nucleus, it deposits energy, causing the xenon to recoil and emit light and electrons that the sensors record. Deep underground, the detector is shielded from cosmic rays and built from low-radioactivity materials, with multiple layers to block (or account for) other particle interactions – letting the rare dark matter interactions stand out.

Seeing into neutrino fog

LZ’s extreme sensitivity now also allows it to detect neutrinos – fundamental, nearly massless particles that are notoriously hard to catch – in a new way. The analysis showed boron-8 solar neutrinos produced by fusion in our sun’s core. This data is a window into how neutrinos interact and the nuclear reactions in stars that produce them. 

But the signal also mimics what researchers expect to see from dark matter. That background noise, sometimes called the “neutrino fog,” could start to compete with dark matter interactions as researchers look for lower-mass particles.

LZ’s new secondary role as a solar neutrino observatory gives theorists more information for their models of neutrinos, which still hold many mysteries themselves. 

Many of the researchers from LZ are also designing a future dark matter detector that uses liquid xenon on an even larger scale. The XLZD detector will combine the best technologies from projects like LZ, XENONnT, and DARWIN for a next-generation WIMP hunter that can also study neutrinos, the sun, cosmic rays, and other unusual candidates for dark matter, such as dark photons and axion-like particles.

LZ is supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, and the National Energy Research Scientific Computing Center, a DOE Office of Science user facility.