Measurement of CP Violation in  \(B_s^0 \rightarrow {} J/\psi \phi \) Decays at  \(\sqrt{s} ={13}\,\textrm{TeV}\) by CMS

The recent measurement of CP violating weak phase \(\phi _s\) in \(B_s^0 \rightarrow {} J/\psi \phi \) decays is presented. The analysis is based on the data of proton-proton collisions corresponding to an integrated luminosity of 96.4 fb \(^{-1}\) recorded at \(\sqrt{s}={13}\,\textrm{TeV}\) with the CMS experiment at CERN-LHC. The decay width (mass) difference \(\Delta \Gamma _s\) ( \(\Delta m_s\) ) between \(B_s^0\) mass eigenstates and the CP violation observable \(|\lambda |\) are also reported. The parameters are extracted by performing a flavor-tagged and time-dependent angular analysis of the \(\mu ^+\mu ^-K^+K^-\) final state. The proceeding discusses these recent results and their combination with the previous CMS measurement at \(\sqrt{s}={8}\,\textrm{TeV}\) , with particular emphasis on the adopted methodology and employed novel opposite-side muon flavor tagger based on Machine Learning techniques.