A new baryon state is observed in the Λ0bπ+π− mass spectrum with high significance using a data sample of pp collisions, collected with the LHCb detector at centre-of-mass energies s√=7,8 and 13TeV, corresponding to an integrated luminosity of 9fb−1. The mass and natural width of the new state are measured to be
where the first uncertainty is statistical and the second systematic. The third uncertainty for the mass is due to imprecise knowledge of the Λ0b baryon mass. The new state is consistent with the first radial excitation of the Λ0b baryon, the Λb(2S)0 resonance. Updated measurements of the masses and the upper limits on the natural widths of the previously observed Λb(5912)0 and Λb(5920)0 states are also reported.
The decays Λb0 → ψ(2S)pK− and Λb0 → J/ψπ+π−pK− are observed in a data sample corresponding to an integrated luminosity of 3 fb−1, collected in proton-proton collisions at 7 and 8 TeV centre-of-mass energies by the LHCb detector. The ψ(2S) mesons are reconstructed through the decay modes ψ(2S) → μ+μ− and ψ(2S) → J/ψπ+π−.The branching fractions relative to that of Λb0 → J/ψpK− are measured to be M(Λ0b)=5619.65±0.17±0.17 MeV/c2,M(Λb0)=5619.65±0.17±0.17 MeV/c2, where the uncertainties are statistical and systematic.
A precision measurement of the 𝐵+𝑐Bc+ meson mass is performed using proton- proton collision data collected with the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to a total integrated luminosity of 9.0 fb−1. The 𝐵+𝑐Bc+ mesons are reconstructed via the decays 𝐵+𝑐Bc+→ J/ψπ+, 𝐵+𝑐Bc+→ J/ψπ+π−π+, 𝐵+𝑐→𝐽/𝜓𝑝𝑝⎯⎯⎯𝜋+Bc+→J/ψpp¯π+, 𝐵+𝑐→𝐽/𝜓𝐷+𝑠Bc+→J/ψDs+, 𝐵+𝑐Bc+→ J/ψ D0K+ and 𝐵+𝑐→𝐵0𝑠𝜋+Bc+→Bs0π+. Combining the results of the individual decay channels, the 𝐵+𝑐Bc+ mass is measured to be 6274.47 ± 0.27 (stat) ± 0.17 (syst) MeV/c2. This is the most precise measurement of the 𝐵+𝑐Bc+ mass to date. The difference between the 𝐵+𝑐Bc+ and 𝐵0𝑠Bs0 meson masses is measured to be 907.75 ± 0.37 (stat) ± 0.27 (syst) MeV/c.