LHCb Collaboration Reports First Evidence of Rare Beauty-Particle Decay
Scientists at CERN's LHCb experiment have observed the first evidence of the ultra-rare decay of a beauty particle into two muons, using an upgraded detector built by University of Liverpool researchers.
The LHCb collaboration at CERN announced the first evidence of the extremely rare decay of a beauty particle (Bd) into two muons, a process predicted to occur in roughly one out of every ten billion beauty particles. The observation, based on data collected after the LHCb upgrade, reaches a statistical significance of 3.2 sigma, short of the five-sigma level required for a formal discovery.
The upgraded experiment incorporates the Vertex Locator (VELO), a silicon-pixel detector assembled by researchers at the University of Liverpool. Positioned just five millimetres from the LHC beams, the VELO enhances particle-tracking precision and enables data collection at up to five times the previous rate, providing the volume of information needed to study such scarce processes.
In addition to the Bd decay evidence, the analysis delivered the most precise measurements to date of the related Bs-to-mu-mu decay, first observed by LHCb in 2015. Both results are consistent with the predictions of the Standard Model, though continued scrutiny of rare decays could reveal physics beyond the current theory.
"That we can see such an incredibly rare decay, that has the potential to tell us so much about the universe, is testament to the skills, ingenuity and real craftsmanship of our talented staff who built the VELO. As this result shows, every member of LHCb can reap the rewards of the VELO's exquisite precision," said Professor Tara Shears, University of Liverpool and LHCb-UK spokesperson.
The findings mark a step forward in probing the so-called “Zeptoverse,” the realm of distances around a billionth of a trillionth of a metre, where undiscovered particles and forces may exist.