Observation of B⁰ → ψ (2S)K⁰ₛ π⁺π⁻ and B⁰ₛ → ψ (2S)K⁰ₛ decays

Abstract

Using a data sample of s√=13TeV proton-proton collisions collected by the CMS experiment at the LHC in 2017 and 2018 with an integrated luminosity of 103~fb−1, the B0s→ψ(2S)K0S and B0→ψ(2S)K0Sπ+π− decays are observed with significances exceeding 5 standard deviations. The resulting branching fraction ratios, measured for the first time, correspond to B(B0s→ψ(2S)K0S)/B(B0→ψ(2S)K0S)=(3.33±0.69(stat)±0.11(syst)±0.34(fs/fd))×10−2 and B(B0→ψ(2S)K0Sπ+π−)/B(B0→ψ(2S)K0S)=0.480±0.013(stat)±0.032(syst), where the last uncertainty in the first ratio is related to the uncertainty in the ratio of production cross sections of B0s and B0 mesons, fs/fd.