Measurement of the CP-violating phase ϕs in the Bs 0→J/ψϕ(1020)→μ+μ−K+K− channel in proton-proton collisions at s=13TeV


Sirunyan A., Tumasyan A., Adam W., Ambrogi F., Bergauer T., Dragicevic M., ...More

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, vol.816, 2021 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 816
  • Publication Date: 2021
  • Doi Number: 10.1016/j.physletb.2021.136188
  • Title of Journal : Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
  • Keywords: CMS, Physics, Oscillations, B physics, QED RADIATIVE-CORRECTIONS, UNIVERSAL MONTE-CARLO, ANGULAR-DISTRIBUTIONS, PHOTOS

Abstract

© 2021 The Author(s)The CP -violating weak phase ϕs and the decay width difference ΔΓs between the light and heavy Bs 0 mass eigenstates are measured with the CMS detector at the LHC in a sample of 48500 reconstructed Bs 0→J/ψϕ(1020)→μ+μ−K+K− events. The measurement is based on a data sample corresponding to an integrated luminosity of 96.4fb−1, collected in proton-proton collisions at s=13TeV in 2017–2018. To extract the values of ϕs and ΔΓs, a time-dependent and flavor-tagged angular analysis of the μ+μ−K+K− final state is performed. The analysis employs a dedicated tagging trigger and a novel opposite-side muon flavor tagger based on machine learning techniques. The measurement yields ϕs=−11±50(stat)±10(syst)mrad and ΔΓs=0.114±0.014(stat)±0.007(syst)ps−1, in agreement with the standard model predictions. When combined with the previous CMS measurement at s=8TeV, the following values are obtained: ϕs=−21±44(stat)±10(syst)mrad, ΔΓs=0.1032±0.0095(stat)±0.0048(syst)ps−1, a significant improvement over the 8 TeV result.