CERN TEAM FINDS FIRST EVIDENCE OF RARE BEAUTY PARTICLE DECAY

The LHCb collaboration at CERN’s Large Hadron Collider has announced the first evidence of a rare particle decay after more than 40 years of searching. The team measured the process, known as Bd → μμ, with a statistical significance of 3.2 sigma, meeting the threshold physicists use to classify evidence. In this decay, a particle containing a beauty quark transforms into two muons, heavier relatives of electrons. The collaboration presented its findings at a seminar on 3 November and in a preprint paper on arXiv, which has not yet undergone peer review.

The Standard Model predicts a frequency around once in every 10 billion beauty particles, with descriptions differing on whether it falls below that rate. The model describes fundamental particles and the forces governing their interactions. Proton collisions at the Large Hadron Collider produce particles containing beauty quarks, also called bottom quarks, which survive briefly before decaying. The researchers attributed their increased sensitivity to an upgrade that boosted LHCb’s collision detection rate and to machine learning techniques that helped distinguish signals from background noise.

The collaboration also announced a more precise measurement of a previously observed related decay. Niladri Sahoo, a University of Birmingham particle physicist and convener of LHCb’s Very Rare Decays working group, described the results as providing “a powerful new test of the Standard Model and a window into potential new physics”. Researchers use rare decays to test whether measured rates match theoretical predictions. They explain that particles beyond the Standard Model could influence those rates without appearing directly in collider experiments.