Deep underground, nearly a mile from the surface, in a former gold mine in South Dakota, one of the most sensitive detectors on the planet is at work. LUX-ZEPLIN, or simply LZ, is a huge tank containing ten tons of ultra-pure liquid xenon. It was built to catch what has so far eluded everyone: particles of dark matter.
The results were presented earlier today by Dr Sam Eriksen of @BristolUni at the TeVPA conference in Tendo, Japan
Dark matter makes up about 85 percent of all matter in the universe. Its gravity holds galaxies together, influences the motion of stars, and shapes the large-scale structure of the cosmos. But it is itself invisible and barely interacts with ordinary matter. For decades, physicists have built ever more precise instruments to catch even a hint of its presence. And then, on September 1, 2026, at the TeV Particle Astrophysics conference in Japan, the LZ collaboration announced a result that made scientists sit up and take notice.
In data collected over 220 'live' days of observations from March 2023 to April 2024, a single event was found. On June 16, 2023, the detector recorded a nuclear recoil — a tiny 'kick' to a xenon nucleus with an energy of about 248 kiloelectronvolts. This occurred in a region of the detector where background processes should be extremely rare. After careful analysis, scientists could not explain the event by known sources: radioactive impurities, neutrons, or cosmic rays that still manage to penetrate the rock overburden.
The statistical significance was 2,6 sigma. The probability that this is a random background fluctuation is about half a percent. For a discovery in particle physics, five sigma is required. So no one is declaring the detection of dark matter. But this is the most intriguing signal LZ has obtained in its entire operational period.
If the event is indeed related to dark matter, the particle must be quite heavy — at least 200 gigaelectronvolts, that is, more than 200 times heavier than a proton. And it must interact differently than in the simplest WIMP models — weakly interacting massive particles. In the classical picture, such high-energy recoils should be accompanied by many weaker ones. They were not seen. This points to more complex possibilities: inelastic interactions or exotic operators in effective field theory.
The collaboration now already has much more data — over 700 days of observations, which have yet to be analyzed blindly. Other experiments, such as XENONnT and PandaX, are also continuing their work. If similar events appear again, the picture could change. If not, this will remain a rare statistical anomaly.
The world we live in is arranged with astonishing precision. Dark matter, which we have not yet touched directly, determines the fate of galaxies and, possibly, the very existence of stars and planets. One barely perceptible pulse in liquid xenon underground is a tiny echo of processes unfolding on the scale of the entire universe. For now, it is only a hint. But it is precisely such hints that once opened new chapters in our understanding of reality.
