Measurement of properties of Bs0 → μ+μ − decays and search for B0 → μ+μ − with the CMS experiment


Sirunyan A., Tumasyan A., Adam W., Ambrogi F., Bergauer T., Brandstetter J., ...More

Journal of High Energy Physics, vol.2020, no.4, 2020 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 2020 Issue: 4
  • Publication Date: 2020
  • Doi Number: 10.1007/jhep04(2020)188
  • Journal Name: Journal of High Energy Physics
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, INSPEC, zbMATH, Directory of Open Access Journals
  • Keywords: B physics, Hadron-Hadron scattering (experiments)
  • Yıldız Technical University Affiliated: Yes

Abstract

Results are reported for the Bs0→ 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 Bs0→ μ+μ− is observed with a significance of 5.6 standard deviations. The branching fraction is measured to be ℬ(Bs0→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 Bs0 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 Bs0→ μ+μ− effective lifetime is measured to be τμ+μ−=1.70−0.44+0.61 ps. These results are consistent with standard model predictions. [Figure not available: see fulltext.].