Measurement of CP violation in $\boldsymbol{B_s^0 \to J/\psi\phi}$ decays at $\boldsymbol{\sqrt{s}=}$ 13 TeV by CMS

The recent measurement of CP violating weak phase $\phi_s$ in $B_s^0 \to J/\psi\phi$ 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 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 $\lvert \lambda \rvert$ 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 TeV, with particular emphasis on the adopted methodology and employed novel opposite-side muon flavor tagger based on ML techniques.