CMS-BPH-21-006: We report a measurement of the Bs to mu+mu- branching fraction and its effective lifetime, as well as results of a search for the B0 to mu+mu-
decay in proton-proton collisions at 13 TeV at the LHC. The analysis is based on data collected with the CMS detector in 2016-2018 corresponding to an integrated luminosity of 140 fb-1
The measured branching fraction of the Bs to mu+mu- decay and the effective Bs lifetime are the most precise measurements to date. No evidence for the B0 to mu+mu-
decay has been found. All results are found to be consistent with the standard model predictions.