There dark matter represents one of the greatest mysteries of modern physics. Although invisibleexercise severity in the Universe, but it does not emit or absorb light. The evolution of the cosmos and galaxies indicates that only a small fraction of matter is visible, such as stars, while the remaining part is attributable to dark matter, which has never been measured until now.
Dark matter and WIMP
In recent years, new experiments have been created to capture traces of dark matter or, better yet, to verify a candidate theory to constitute dark matter, formed by weakly interacting massive particles called WIMP (Weakly Interacting Massive Particle). These particles interact weakly with ordinary matter and are therefore difficult to detect.
The LUX-ZEPLIN project marks an important step
One of these new experiments is the project LUX-ZEPLIN (LZ)the world’s most sensitive underground liquid xenon detector installed one mile underground within the Sanford Underground Research Facility, USA.
Its purpose is search for rare interactions of hypothetical dark matter particles with xenon nuclei. The impact could produce a flash of light and an electrical signal that the detector is designed to measure.)
The new results and the latest discoveries
In 280 days of acquisitionLZ achieved record exposure, analyzing 4.2 tons of material per year, achieving 5 times greater sensitivity compared to the best ever achieved before. From the analyzes it appears that there are no dark matter particles with a mass greater than 9 GeV/c2i.e. greater than approximately 1.60 × 10⁻²6 kg.
As a comparison, think that the mass of the proton is equal to 0.938 GeV/c2 and that 1 GeV/c² is equivalent to approximately 1.78 × 10⁻²⁷ kg.
This negative result is not a failure: it helps researchers to discard some areas where WIMPs cannot hide. This result more stringently limits the cross section, i.e. the probability of interaction that dark particles could have with nucleons.
Scott Haselschwardtphysics coordinator of the LZ project, said: “We are pushing the boundaries in a regime where people have never looked for dark matter before.” He added: “There’s a human tendency to want to see patterns in data, so it’s really important, when you go into this new regime, that no bias comes into play. If you make a discovery, you want it to be correct.” Thanks to the LZ experiment, researchers are closer to delineating what dark matter cannot be. The new measurements narrow the field of possibilities, helping theoretical physicists to focus on regions of mass and interaction that are still possible.
The LZ experiment involves collect data for 1,000 days before its conclusion in 2028, to explore new regions. Furthermore, the challenge of the coming years for this sector is that of improve sensitivity of future detectors and explore regions that now remain out of reach.
