The LHCb collaboration at CERN reported the first evidence of a neutral beauty meson (B⁰) decaying into two muons, a process predicted to occur about once in every 10 billion such particles [sci.news][phys.org]. Combining the new result with earlier LHCb data gave the signal a statistical significance of 3.2 standard deviations—enough to count as evidence, but below the five-standard-deviation threshold for a discovery [sci.news][reddit.com]. The measured rate is consistent with the Standard Model, the leading theory of particle physics [sci.news][moneycontrol.com]. Rare decays can be sensitive to effects from particles that are not produced directly in collisions [phys.org][orf.at]. Researchers plan to continue collecting data into the early 2030s to refine the measurement; a further detector upgrade is also planned [phys.org][moneycontrol.com]. Highlights: • Related decay: For the heavier Bₛ⁰ meson decaying into two muons, LHCb measured a branching fraction of 3.31 per billion, compared with a Standard Model prediction of 3.66 per billion [sci.news]. • Branching fraction: LHCb measured the B⁰ decay at 1.26 in 10 billion in the new data alone, compared with the Standard Model prediction of 1.03 in 10 billion; the combined result is 1.14 in 10 billion [sci.news]. • Data collection: The upgraded LHCb detector records collisions at up to five times its previous rate, and researchers combined 2024–25 data with observations from 2011–18 [reddit.com][watson.ch]. • UK funding: The UK Research and Innovation agency withdrew its planned contribution to the LHCb upgrade, while saying Britain remains CERN’s second-largest funder at about £175 million a year [bbc.co.uk]. Perspectives: Professor Tim Gershon, LHCb collaboration leader: He warned that UK funding cuts put the country's full participation in the research at risk and could reduce opportunities to train early-career scientists [bbc.co.uk]. (BBC News) UK Research and Innovation: The agency said it selected other infrastructure projects after reviewing competing funding bids [bbc.co.uk]. (BBC News) Professor Brian Cox, University of Manchester particle physicist: He criticized the UK funding reduction, saying it could damage future research and the country's scientific reputation [bbc.co.uk][slate.fr]. (BBC News) "To see something that people had been searching for since before I was born was a real privilege." — Dr. Harry Cliff, physicist at the University of Cambridge’s Cavendish Laboratory Sources: • CERN Physicists Find Evidence of Ultra-Rare Particle Decay - sci.news • Physicists find first evidence of rarest beauty particle decay at CERN - reddit.com • Physicists step closer to the 'Zeptoverse' after 42-year particle search - phys.org • Scientists detect signals at the smallest scale ever explored - bbc.co.uk • Forschende stossen am Cern auf seltenen Teilchenzerfall - watson.ch • What is the "Zeptoverse"? CERN scientists find evidence of rare particle decay after 42 years - moneycontrol.com • Seltener Teilchenzerfall beobachtet - orf.at • Haruldane lagunemisprotsess avas akna zeptouniversumisse - err.ee • Qué es el "zeptoverso", el mundo más pequeño jamás detectado en la naturaleza, y por qué es clave para entender el universo - bbc.com • Ανακαλύφθηκε το «ζεπτοσύμπαν» ο μικρότερος υποατομικός κόσμος που μπορεί να αποκαλύψει θεμελιώδη μυστικά της φύσης - naftemporiki.gr • Des scientifiques ont ouvert une porte vers un monde 100 milliards de fois plus petit qu'un atome - slate.fr • Naučnici registrovali signale na skali 100 milijardi puta manjoj od atoma - nezavisne.com • Сигналы из «зептовселенной»: новое открытие приближает обнаружение темной материи - bbc.com --- 📰 Story aggregated by Kagi News