Measurement of properties of B0s to mu+ mu- decays and search for B0 to mu+ mu- with the CMS experimentстатья
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Дата последнего поиска статьи во внешних источниках: 7 октября 2020 г.
Аннотация:Results are reported for the B0s→μ+μ− branching fraction and effective lifetime and from a search for the decay B0→μ+μ−. The analysis uses a data sample of proton-proton collisions accumulated by the CMS experiment in 2011, 2012, and 2016, with center-of-mass energies (integrated luminosities) of 7 TeV (5 fb−1), 8 TeV (20 fb−1), and 13 TeV (36 fb−1). The branching fractions are determined by measuring event yields relative to B+→ J/ψK+ decays (with J/ψ→μ+μ−), which results in the reduction of many of the systematic uncertainties. The decay B0s→μ+μ− is observed with a significance of 5.6 standard deviations. The branching fraction is measured to be B(B0s→μ+μ−) = [2.9 ± 0.7 (exp) ± 0.2 (frag)] × 10−9, where the first uncertainty combines the experimental statistical and systematic contributions, and the second is due to the uncertainty in the ratio of the B0s and the B+ fragmentation functions. No significant excess is observed for the decay B0→μ+μ−, and an upper limit of B(B0→μ+μ−) < 3.6 × 10−10 is obtained at 95% confidence level. The B0s→μ+μ− effective lifetime is measured to be τμ+μ− = 1.70 +0.61−0.44 ps. These results are consistent with standard model predictions.