Researchers involved in the LZ experiment, an international collaboration of around 250 scientists and engineers, have identified a single particle interaction that they are struggling to explain. The analysis, led by the LZ group at the University of Bristol, suggests a potential hint of dark matter.
Dark matter is believed to constitute approximately 85% of all matter in the universe but has never been directly detected. The LZ detector, located nearly a mile underground in South Dakota, US, uses 10 tonnes of ultrapure liquid xenon to search for weakly interacting massive particles (WIMPs).
The result has a 2.6 sigma significance, meaning there is roughly a 0.5% chance it could be explained by known backgrounds alone. This falls short of the 5-sigma threshold required in physics to claim a discovery. If the event was caused by dark matter, it would point to a WIMP with a mass of at least 200 GeV/c², which is more than 200 times the mass of a proton.
The UK plays a significant role in the LZ experiment, with 10 UK teams involved in its construction and operations, funded by the Science and Technology Facilities Council (STFC). The LZ experiment will continue collecting data, allowing researchers to further investigate this intriguing signal.