EPJ Web of Conferences 49, 03003 (2013)
https://doi.org/10.1051/epjconf/20134903003

New results on the search for B_s⁰ → µ⁺µ⁻ from LHCb

¹ CERN, Geneva, Switzerland
² TU Dortmund, Dortmund, Germany

^a e-mail: Burkhard.Schmidt@cern.ch

Abstract

A search for the rare decays B_s⁰ → 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 B_s⁰ → 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 (B_s⁰ → 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.