# Measurement of the $B^0_s \to \mu^+ \mu^-$ branching fraction and search for $B^0 \to \mu^+ \mu^-$ decays at the LHCb experiment

Abstract : A search for the rare decays $B^0_s \to\mu^+\mu^-$ and $B^0 \to\mu^+\mu^-$ is performed at the LHCb experiment. The data analysed correspond to an integrated luminosity of 1 fb$^{-1}$ of $pp$ collisions at a centre-of-mass energy of 7 TeV and 2 fb$^{-1}$ at 8 TeV. An excess of $B^0_s \to\mu^+\mu^-$ signal candidates with respect to the background expectation is seen with a significance of 4.0 standard deviations. A time-integrated branching fraction of ${\cal B}(B^0_s \to\mu^+\mu^-) = (2.9^{+1.1}_{-1.0})\times 10^{-9}$ is obtained and an upper limit of ${\cal B}(B^0 \to\mu^+\mu^-) < 7.4\times 10^{-10}$ at 95% confidence level is set. These results are consistent with the Standard Model expectations.
Document type :
Journal articles
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http://hal.in2p3.fr/in2p3-00846339
Contributor : Danielle Cristofol <>
Submitted on : Friday, July 19, 2013 - 8:18:20 AM
Last modification on : Thursday, February 25, 2021 - 10:58:21 AM

### Citation

R. Aaij, B. Adeva, M. Adinolfi, C. Adrover, A. Affolder, et al.. Measurement of the $B^0_s \to \mu^+ \mu^-$ branching fraction and search for $B^0 \to \mu^+ \mu^-$ decays at the LHCb experiment. Physical Review Letters, American Physical Society, 2013, 111, pp.101805. ⟨10.1103/PhysRevLett.111.101805⟩. ⟨in2p3-00846339⟩

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