Observation of Cabibbo-Suppressed Two-Body Hadronic Decays and Precision Mass Measurement of the ωc0 Baryon

The first observation of the singly Cabibbo-suppressed ωc0→ω-K+ and ωc0→Ξ-π+ decays is reported, using proton-proton collision data at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb-1, collected with the LHCb detector between 2016 and 2018. The branching fraction ratios are measured to be B(ωc0→ω-K+)B(ωc0→ω-π+)=[6.08±0.51(stat)±0.40(syst)]%,B(ωc0→Ξ-π+)B(ωc0→ω-π+)=[15.81±0.87(stat)±0.44(syst)±0.16(ext)]%. In addition, using the ωc0→ω-π+ decay channel, the ωc0 baryon mass is measured to be M(ωc0)=2695.28±0.07(stat)±0.27(syst)±0.30(ext) MeV, improving the precision of the previous world average by a factor of 4.