Measurement of the B-s(0) -> mu(+)mu(-) decay properties and search for the B-0 -> mu(+)mu(-) and B-s(0) -> mu(+)mu(-) gamma decays

An improved measurement of the decay B0s → μþμ− and searches for the decays B0 → μþμ− and B0s → μþμ−γ are performed at the LHCb experiment using data collected in proton-proton collisions at pffiffi −1 s 1⁄4 7, 8 and 13 TeV, corresponding to integrated luminosities of 1, 2 and 6 fb , respectively. The B0s → μþμ− branching fraction and effective lifetime are measured to be BðB0s → μþμ−Þ 1⁄4 ð3.09þ0.46þ0.15Þ × 10−9 and τðB0 → μþμ−Þ 1⁄4 ð2.07 0.29 0.03Þ ps, respectively, where the uncertain- −0.43−0.11 s ties include both statistical and systematic contributions. No significant signal for B0 → μþμ− and B0s → μþμ−γ decays is found and the upper limits BðB0 → μþμ−Þ < 2.6 × 10−10 and BðB0s → μþμ−γÞ < 2.0 × 10−9 at 95% confidence level are determined, where the latter is limited to the range mμμ > 4.9 GeV=c2. Additionally, the ratio between the B0 → μþμ− and B0s → μþμ− branching fractions is measured to be Rμþ μ− < 0.095 at 95% confidence level. The results are in agreement with the Standard Model predictions.