Observation of Overlapping Spin-1 and Spin-3 D^¯0K^- Resonances at Mass 2.86 GeV/c²

The resonant substructure of Bs0→D¯0K-π+ decays is studied using a data sample corresponding to an integrated luminosity of 3.0fb-1 of pp collision data recorded by the LHCb detector. An excess at m(D¯0K-)≈2.86GeV/c2 is found to be an admixture of spin-1 and spin-3 resonances. Therefore, the DsJ∗(2860)- state previously observed in inclusive e+e-→D¯0K-X and pp→D¯0K-X processes consists of at least two particles. This is the first observation of a heavy flavored spin-3 resonance, and the first time that any spin-3 particle has been seen to be produced in B decays. The masses and widths of the new states and of the Ds2∗(2573)- meson are measured, giving the most precise determinations to date.