New results on the search for Bs0 → µ+µ− from LHCb
1 CERN, Geneva, Switzerland
2 TU Dortmund, Dortmund, Germany
a e-mail: Burkhard.Schmidt@cern.ch
A search for the rare decays Bs0 → µ+µ− and B0 → μ+μ− is performed with the LHCb experiment using 1.1 fb−1 of data collected at √s = 8 TeV and 1.0 fb−1 of data collected at √s = 7 TeV. An excess of Bs0 → µ+µ− candidates with respect to the background expectations is observed with a statistical significance of 3.5 standard deviations. A branching fraction of ℬ (Bs0 → µ+µ−) = (3.2−1.2+1.5) × 10−9 is measured with an unbinned maximum likelihood fit. The measured branching fraction is in agreement with the expectation from the Standard Model. The observed number of B0 → μ+μ− candidates is consistent with the background expectation and an upper limit on the branching fraction of ℬ(B 0 → μ+μ−) < 9.4 × 10−10 is obtained.
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