A study of the decays Bs0→μ+μ- and B0→ μ+μ- has been performed using data corresponding to an integrated luminosity of 25 fb- 1 of 7 and 8 TeV proton–proton collisions collected with the ATLAS detector during the LHC Run 1. For the B0 dimuon decay, an upper limit on the branching fraction is set at B(B0→ μ+μ-) < 4.2 × 10 - 10 at 95 % confidence level. For Bs0, the branching fraction B(Bs0→μ+μ-)=(0.9-0.8+1.1)×10-9 is measured. The results are consistent with the Standard Model expectation with a p value of 4.8 %, corresponding to 2.0 standard deviations.
Aaboud, M., Aad, G., Abbott, B., Abdallah, J., Abdinov, O., Abeloos, B., et al. (2016). Study of the rare decays of Bs0 and B0 into muon pairs from data collected during the LHC Run 1 with the ATLAS detector. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 76(9) [10.1140/epjc/s10052-016-4338-8].