Precision measurement of the B+c meson mass
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.