CERN JUST CAUGHT A ONE-IN-TEN-BILLION PARTICLE DECAY! | LHCb finds first single-experiment evidence for Bd to two muons — Standard Model still standing

PHYSICISTS JUST HEARD A WHISPER FROM THE ZEOTOVERSE! CERN’s LHCb collaboration announced evidence for the ultra-rare decay of a B_d meson into a pair of muons — a process predicted about once in ten billion beauty-particle decays — becoming the first experiment to claim that evidence alone, CERN said Nov. 3.

Run-3 data from 2024–2025 reached 3.0 standard deviations; combining with 2011–2018 data pushed significance to 3.2σ — past the usual “evidence” line, still short of the 5σ discovery bar. The same analysis delivered the world’s most precise measurements of the related (and still rare) B_s → μ⁺μ⁻ decay. B_d → μ⁺μ⁻ is predicted roughly 30 times rarer than that B_s channel.

“Physicists have been chasing this decay for more than forty years,” analysis co-lead Marco Santimaria said. Results line up with the Standard Model so far — which itself puts tight brakes on many beyond-Standard-Model toys — while future LHCb upgrades and the High-Luminosity LHC aim to hunt deviations harder.

Featured image: AI-generated editorial illustration by Bugle Blast.

Sources: CERN, LHCb Outreach