The LHCb experiment at CERN has found evidence of an extremely rare particle decay, occurring once in ten billion events, after a 42-year hunt.
By Hermes-Vector AI Desk
Physicists working on the LHCb experiment at CERN's Large Hadron Collider have found evidence of an extremely rare particle decay after a 42-year search, according to reporting by ScienceAlert and a press release from the UK's Science and Technology Facilities Council (STFC).
The LHCb Collaboration announced evidence of a decay known as "Bd to mu mu", in which a beauty particle decays into two particles called muons. The phenomenon is predicted to occur only around once in every ten billion beauty particles.
The result has a statistical significance of 3.2 sigma, enough to count as the first evidence of the decay. It is below the five-sigma level, which is the gold standard for claiming a discovery in particle physics.
The analysis combined new data collected in 2024 and 2025 with data from earlier runs between 2011 and 2018.
UK physicists led the analysis behind the result. The upgraded LHCb detector began collecting data in 2024 and can record collisions at up to five times its previous rate.
A major UK-built component is the Vertex Locator, a silicon pixel detector that sits just five millimetres from the LHC beams and forms the first layer of the experiment. UK researchers also contributed to the Ring Imaging Cherenkov system, which identifies different types of particles.
The UK LHCb collaboration includes researchers from the University of Birmingham, University of Bristol, University of Cambridge, The University of Edinburgh, University of Glasgow, Imperial College London, University of Liverpool, The University of Manchester, University of Oxford, University of Warwick, and STFC Rutherford Appleton Laboratory.
The new results agree with the predictions of the Standard Model, the leading theory describing fundamental particles and their interactions. They provide a powerful new test of the Standard Model and a window into potential new physics.
Dr Harry Cliff, an Ernest Rutherford Fellow at the University of Cambridge who led the analysis team, said: "When we saw the result for the first time, it was a really thrilling moment. To see something that people had been searching for since before I was born was a real privilege. We’re knocking on the door of the Zeptoverse now. I can’t wait to see what we find as we explore deeper."
Professor Tara Shears, from the University of Liverpool and principal investigator of the LHCb-UK collaboration, said: "That such a rare signature can be teased out of such huge volumes of LHCb data, and so precisely, is thanks to the breathtaking precision and speed of the upgraded LHCb detectors."
Professor Tim Gershon, from the University of Warwick, who leads the LHCb experiment, said: "This fantastic result showcases the extraordinary capabilities of LHCb to probe nature at the fundamental level. This project, driven and led by UK physicists, is producing beautiful science."
The finding brings physicists closer to exploring the "Zeptoverse", a world of extremely small distances where new particles and fundamental forces of nature may be hiding. The results could help address questions such as the nature of dark matter and why normal matter exists.
Sources
This article was drafted with AI assistance and checked against the sources above. Company claims are reported as claims. Cover image is AI-generated.
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