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Journal Articles Physical Review Letters Year : 2013

First evidence for the decay Bs -> mu+ mu-

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R. Aaij
  • Function : Author
J. He
Marie Nicol
  • Function : Author
  • PersonId : 901312
J. Cogan
O. Leroy
J. Serrano

Abstract

A search for the rare decays Bs->mu+mu- and B0->mu+mu- is performed using data collected in 2011 and 2012 with the LHCb experiment at the Large Hadron Collider. The data samples comprise 1.1 fb^-1 of proton-proton collisions at sqrt{s} = 8 TeV and 1.0 fb^-1 at sqrt{s}=7 TeV. We observe an excess of Bs -> mu+ mu- candidates with respect to the background expectation. The probability that the background could produce such an excess or larger is 5.3 x 10^-4 corresponding to a signal significance of 3.5 standard deviations. A maximum-likelihood fit gives a branching fraction of BR(Bs -> mu+ mu-) = (3.2^{+1.5}_{-1.2}) x 10^-9, where the statistical uncertainty is 95% of the total uncertainty. This result is in agreement with the Standard Model expectation. The observed number of B0 -> mu+ mu- candidates is consistent with the background expectation, giving an upper limit of BR(B0 -> mu+ mu-) < 9.4 x 10^-10 at 95% confidence level.

Dates and versions

in2p3-00751272 , version 1 (13-11-2012)

Identifiers

Cite

R. Aaij, S. Barsuk, O. Callot, J. He, B. Jean-Marie, et al.. First evidence for the decay Bs -> mu+ mu-. Physical Review Letters, 2013, 110, pp.021801. ⟨10.1103/PhysRevLett.110.021801⟩. ⟨in2p3-00751272⟩
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