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## Observation of a new Ξ0b state

Aaij R., Arzymatov K., Belavin V., Boldyrev A., Borisyak M., Derkach D., Hushchyn M., Kazeev N., Maevskiy A., Popov S., Ratnikov F., Ryzhikov A., Ustyuzhanin A., Zunica G.

Using a proton-proton collision data sample collected by the LHCb experiment, corresponding to an integrated luminosity of 8.5  fb−1, the observation of a new excited Ξ0b resonance decaying to the Ξ−bπ+final state is presented. The state, referred to as Ξb(6227)0, has a measured mass and natural width of m(Ξb(6227)0)=6227.1+1.4−1.5±0.5  MeV and Γ(Ξb(6227)0)=18.6+5.0−4.1±1.4  MeV, where the uncertainties are statistical and systematic. The production rate of the Ξb(6227)0 state relative to that of the Ξ−b baryon in the kinematic region 2<η<5 and pT<30  GeV is measured to be fΞb(6227)0fΞ−bB(Ξb(6227)0→Ξ−bπ+)=0.045±0.008±0.004, where B(Ξb(6227)0→Ξ−bπ+) is the branching fraction of the decay, and fΞb(6227)0 and fΞ−b represent fragmentation fractions. Improved measurements of the mass and natural width of the previously observed Ξb(6227)− state, along with the mass of the Ξ−b baryon, are also reported. Both measurements are significantly more precise than, and consistent with, previously reported values.