Observation of the decays $ B^{0}\to\psi(2S)K^{0}_{S}\pi^{+}\pi^{-} $ and $ B^{0}_{S} \to \psi(2S)K^{0}_{S} $ at $\sqrt{s}$ = 13 TeV in the CMS experiment

The decays $B^{0}\to\psi(2S)K^{0}_{S}\pi^{+}\pi^{-}$ and $B^{0}_{S}\to\psi(2S)K^{0}_{S}$ are observed for the first time using data samples (2017 and 2018) of pp collisions collected with the CMS detector, corresponding to an integrated luminosity 103 fb$^{-1}$ taken at $\sqrt{s}$ = 13 TeV. These decays are observed with a significance exceeding five standard deviations. In this study, the branching fraction of both decays $B^{0}_{S}\to\psi(2S)K^{0}_{S}$ and $B^{0}\to\psi(2S)K^{0}_{S}\pi^{+}\pi^{-}$ relative to the $B^{0}\to\psi(2S)K^{0}_{S}$ decay are measured.