LHCb Physicists working on the experiment at CERN have spotted a rare decay of a B meson. (Courtesy: CERN)"> LHCb Physicists working on the experiment at CERN have spotted a rare decay of a B meson. (Courtesy: CERN)

The LHCb collaboration at CERN’s Large Hadron Collider (LHC) reports the first evidence from a single experiment that the beauty meson B⁰ can decay into a muon and an antimuon. If confirmed, it would be the rarest B-meson decay yet observed. A similar decay of the B⁰ S meson was also measured at record precision. The results agree with the Standard Model of particle physics, and this constrains theories that aim to explain anomalies in other B-meson decays.

While the Standard Model does a good job of describing the known elementary particles and forces, it is not complete. It cannot explain the nature of dark matter, for example, or why the universe contains far more matter than antimatter.…