# CERN Detects Rare Particle Decay After Four Decades of Searching Physicists identify a decay occurring once in ten billion beauty particle events. - **Source:** [ScienceDaily – Top](https://www.sciencedaily.com) - **Published:** 2026-11-10 - **Topic:** [science](https://brifing.si/c/science) - **Original article:** - **On Brifing:** https://brifing.si/s/b686e75e-2392-4fe1-88b6-eca2a2f004b3 ## Rare Particle Decay Evidence Physicists at CERN have reached a significant milestone by detecting evidence of the B d particle decay into two muons. This process is exceptionally rare, expected to occur only once in approximately 10 billion beauty particle decays. The discovery marks the first time a single experiment has successfully captured this specific event. ## Significance of Golden Channels The decay process is categorized as a golden channel for investigating physics beyond the Standard Model. Because quantum effects allow heavy, undiscovered particles to influence decay rates, these measurements provide indirect evidence of new physics. Scientists analyze these subtle discrepancies to determine if the known laws of nature require further expansion. ## Technological Advancements in Detection Researchers utilized a major upgrade to the LHCb experiment, which began collecting data in 2024 at five times the previous rate. By integrating advanced machine learning techniques, the team successfully distinguished these rare signals from the massive background noise. Without these technical improvements, the elusive decay would have remained completely undetectable. ## Statistical Thresholds and Significance The team achieved a statistical significance of 3.2 standard deviations by combining 2024-2025 data with measurements from 2011 to 2018. While this exceeds the 3.0 threshold required for evidence, it remains below the 5.0 standard deviation mark needed to claim a confirmed observation. Further data is required to reach that definitive milestone. ## Comparison with B s Decay Scientists previously observed a related process involving the B s particle in 2015. The B s decay is significantly more common, occurring three times per billion beauty particle decays, whereas the B d process is roughly 30 times less frequent. This new study also provided the most precise measurements ever recorded for B s. ## Future High Luminosity Upgrades The High Luminosity LHC, scheduled for operation in 2030, promises to increase data collection rates by another factor of ten. These future upgrades will allow physicists to observe significantly more of these rare decays. Increased sensitivity will enable researchers to probe deeper into the existence of particles currently beyond direct accelerator reach. ## The Role of Muons The decay involves a B d particle, containing a beauty quark and a down antiquark, transforming into a pair of muons. Muons are fundamental particles similar to electrons but possess greater mass. Observing their behavior during this specific annihilation process provides critical data for testing the accuracy of the current Standard Model. ## Long-Term Scientific Impact After forty years of searching, this evidence represents a long-awaited advance for the international team of 19 scientists. The findings offer a promising pathway to determine if the Standard Model is part of a larger physical framework. Continued research will focus on achieving the five-sigma threshold to confirm this rare phenomenon. ## Sources covering this story - https://www.sciencedaily.com/releases/2026/11/261108233047.htm — --- _Summary written by Brifing from the original reporting. Copyright in the original article belongs to its publisher; read the full piece at the link above._