LZ Sees Surprising Result in Search for Dark Matter

Scientists have been studying dark matter for almost a century. This invisible substance accounts for around 85 per cent of all matter in the universe. However, no particle has ever been directly detected.
Now, it seems that we have come one step closer: the international LUX-ZEPLIN (LZ) experiment has recorded an interaction between individual particles for the first time. While only one particle has been detected thus far, this cannot be explained by known phenomena. 'Although the result does not yet reach the statistical threshold required to announce a discovery, it represents the most convincing evidence of dark matter to date,' states the press release from the LZ consortium, issued 1 September 2026.

The LUX-ZEPLIN experiment, launched in 2012, is searching for dark matter. UZH is playing a key role in this project. A team led by Björn Penning from the University of Zurich's Institute of Physics is also involved in the project. With eight researchers, the team is one of the largest university groups within the LZ experiment, carrying out important tasks. Björn Penning founded and initially led the High-Nuclear-Recoil group, whose work has yielded the latest results, before passing leadership on to another colleague in accordance with the rotation system. Today, two postdoctoral researchers and a PhD student from UZH are working in this group.

Press release by the LZ experiment:
LZ Sees Surprising Result in Search for Dark Matter

The LUX-ZEPLIN experiment observed a particle interaction that could be interpreted as a signal from WIMPs, a dark matter candidate — but researchers will need more data to confirm.

For the better part of a century, people have been trying to understand dark matter. This invisible substance makes up roughly 85% of the mass in the universe but has never been directly detected. Determining exactly what it is remains one of the biggest questions about our world.

Now, a new analysis from the LUX-ZEPLIN (LZ) experiment has recorded a single particle interaction that researchers have great difficulty explaining with known background signals from normal matter. The result does not yet meet the statistical threshold required to claim a discovery, but is the most compelling hint of dark matter reported by the experiment to date.

LZ is an international collaboration of 250 scientists and engineers from 39 institutions among them the UZH group of Prof. Björn Penning. The detector is managed by the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and operates nearly one mile below ground at the Sanford Underground Research Facility (SURF) in South Dakota. The experiment uses 10 tonnes of ultrapure liquid xenon to search for dark matter and is optimized to look for WIMPs, or weakly interacting massive particles.

The results were presented in a scientific talk at the 2026 TeV Particle Astrophysics conference in Japan. The paper will be released on the online repository arXiv and submitted to the journal Physical Review Letters.

“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,” said Rick Gaitskell, a professor at Brown University and the spokesperson for LZ. “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.”