Evidence for the decay BS0→K¯∗0 μ+ μ−

Abstract

Abstract: A search for the decay B0 s → K ∗0 µ +µ − is presented using data sets corresponding to 1.0, 2.0 and 1.6 fb−1 of integrated luminosity collected during pp collisions with the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, respectively. An excess is found over the background-only hypothesis with a significance of 3.4 standard deviations. The branching fraction of the B0 s → K ∗0 µ +µ − decay is determined to be B(B0 s → K ∗0 µ +µ −) = [2.9 ± 1.0 (stat) ± 0.2 (syst) ± 0.3 (norm)] × 10−8 , where the first and second uncertainties are statistical and systematic, respectively. The third uncertainty is due to limited knowledge of external parameters used to normalise the branching fraction measurement.