Physical Review D, vol.109, no.11, 2024 (SCI-Expanded)
The Formula Presented decay has been observed with a statistical significance in excess of five standard deviations. The analysis is based on an event sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment in 2018 and corresponding to an integrated luminosity of Formula Presented. Normalizing to the Formula Presented decay mode leads to a branching fraction of Formula Presented, a value that is consistent with the standard model prediction.