Branching Fraction Measurements of the Rare B0s→ϕμ+μ− and B0s→f′(1525)μ+μ− Decays

The branching fraction of the rare B0s→ϕμ+μ− decay is measured using data collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to integrated luminosities of 1, 2, and 6  fb−1, respectively. The branching fraction is reported in intervals of q2, the square of the dimuon invariant mass. In the q2 region between 1.1 and 6.0  GeV2/c4, the measurement is found to lie 3.6 standard deviations below a standard model prediction based on a combination of light cone sum rule and lattice QCD calculations. In addition, the first observation of the rare B0s→f′2(1525)μ+μ− decay is reported with a statistical significance of 9 standard deviations and its branching fraction is determined.