Observation of B 0 → ψ (2S)K 0 S π + π − and B 0 s → ψ (2S)K 0 S decays

Abstract

t Using a data sample of √s = 13 TeV protonproton 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)K0 S) =(3.33 ± 0.69(stat) ± 0.11 (syst) ± 0.34 ( fs/ fd)) × 10−2and B(B0 → ψ(2S)K0Sπ+π−)/B(B0 → ψ(2S)K0 S) =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 B0mesons, fs/ fd.