Measurement of the B_s~0 →μ~+μ~- Branching Fraction and Search for B~0 →μ~+μ~- Decays at the LHCb Experiment

摘要

A search for the rare decays B_s~0 →μ~+μ~- and B~0 →μ~+μ~- is performed at the LHCb experiment. The data analyzed correspond to an integrated luminosity of 1 fb~(-1) of pp collisions at a center-of-mass energy of 7 TeV and 2 fb~(-1) at 8 TeV. An excess of B_s~0 →μ~+μ~- signal candidates with respect to the background expectation is seen with a significance of 4.0 standard deviations. A time-integrated branching fraction of B(B_s~0 →μ~+μ~-) = (2.91_(-1.0)~(1.1)) × 10~(-9) is obtained and an upper limit of B(B~0 →μ~+μ~-) ＜ 7.4 × 10~(-10) at 95% confidence level is set. These results are consistent with the standard model expectations.