Physicists using the upgraded Large Hadron Collider beauty experiment at CERN detected evidence of a rare particle decay occurring once in every ten billion beauty particles, according to announcements on November 3, 2026. The result brings researchers closer to probing the zeptoverse, a subatomic scale where unknown particles and forces of nature may reside.
Detecting Rare Beauty Particle Decays
The research focuses on the decay of a short-lived particle containing a beauty quark and a down antiquark, known as a Bd meson, into two particles called muons. Beauty quarks are heavier relatives of the up and down quarks that compose ordinary atomic matter. These particles survive for approximately 1.5 trillionths of a second before breaking down.
That brief window gives physicists a method to examine physical processes at extremely small distance scales.
The Large Hadron Collider can probe distances of around 100 zeptometers. This scale is equivalent to a trillionth of a billionth of a meter.
The international team combined data collected between 2024 and 2025 with historical measurements from runs spanning 2011 to 2018. Using machine-learning techniques and improved particle identification, researchers separated the faint signals of the rare decay from an overwhelming background of particle collisions.
The analysis yielded a statistical significance of 3.2 standard deviations. This surpasses the three-sigma threshold required to claim evidence of a new phenomenon. However, the result sits below the five-sigma level required to officially declare a discovery in particle physics.
Testing the Standard Model of Physics
The measurement aligns with the predictions of the Standard Model, the leading theoretical framework describing fundamental particles and their interactions, according to UKRI. Rare decays are particularly sensitive to quantum influences from heavy, undiscovered particles. Precise observations can reveal cracks in current physics theories.
Researchers pursued the decay process for over four decades across multiple international facilities. The work began in the early 1980s with the CLEO experiment at Cornell in the United States.
Professor Chris Parkes, Head of the Department of Physics and Astronomy at The University of Manchester, detailed the scale of the hardware improvements behind the finding.
The upgraded LHCb was a major undertaking – a fifteen-year design and construction project from a 1900 international member collaboration.
We’re knocking on the door of this zeptoverse.
Future Detector Upgrades at CERN
The upgraded detector operates at five times the collision recording rate of previous runs, capturing a larger sample of particles for analysis. Professor Tim Gershon from the University of Warwick, who leads the LHCb experiment, pointed to the breadth of the research.
Further verification of the Bd decay will require achieving a five-sigma significance level.
Planned infrastructure updates include the start-up of the High-Luminosity Large Hadron Collider in 2030. An upcoming detector upgrade is scheduled for the middle of the next decade, with both projects aiming to increase data collection rates by another order of magnitude.
Earlier coverage: Large Hadron Collider finds evidence of Big Bang matter in small collisions