Aaboud, M.Aad, G.Abbott, B.Abbott, D. C.Abdinov, O.Abeloos, B.Abhayasinghe, D. K.Izen, Joseph M.Meirose, BernhardReeves, KendallATLAS Collaboration2019-10-252019-10-252019-04-151126-6708https://hdl.handle.net/10735.1/7041A study of the decays B{_{s}⁰} → μ⁺μ⁻ and B⁰ → μ⁺μ⁻ has been performed using 26.3 fb⁻¹ of 13 TeV LHC proton-proton collision data collected with the ATLAS detector in 2015 and 2016. Since the detector resolution in μ⁺μ⁻ invariant mass is comparable to the B{_{s}⁰} -B⁰ mass difference, a single fit determines the signal yields for both decay modes. This results in a measurement of the branching fraction ℬ(B{_{s}⁰} → μ+μ−) = (3.2 _{−1.0} ^{+1.1}) × 10⁻⁹ and an upper limit ℬ (B⁰ → μ⁺μ⁻) < 4.3 × 10⁻¹⁰ at 95% confidence level. The result is combined with the Run 1 ATLAS result, yielding ℬ(B{_{s}⁰} → μ+μ−)=(2.8{_{−0.7} ^{+0.8}}) × 10⁻⁹ and ℬ (B⁰→ μ⁺μ⁻) < 2.1 × 10⁻¹⁰ at 95% confidence level. The combined result is consistent with the Standard Model prediction within 2.4 standard deviations in the ℬ(B⁰ → μ⁺μ⁻)−ℬ(B{_{s}⁰} → μ⁺μ⁻) plane. © 2019 CERN, for the ATLAS CollaborationenCC BY 4.0 (Attribution)©2019 CERN, for the ATLAS Collaborationhttp://creativecommons.org/licenses/by/4.0/Hadrons--ScatteringProton-proton interactionsBranching fractions (Nuclear physics)Standard model (Nuclear physics)articleAaboud, M., G. Aad, B. Abbott, D. C. Abbott, et al. 2019. "Study of the rare decays of B{_{s}⁰} and B⁰ mesons into muon pairs using data collected during 2015 and 2016 with the ATLAS detector." Journal of High Energy Physics 2019(4): art. 098, doi: 10.1007/JHEP04(2019)09820194