Measurement of b-hadron Masses

Measurements of b-hadron masses are performed with the exclusive decay modes B+ → J/ψ K+, B0 → J/ψK*0, B0 → J/ψ K0S , B0s → J/ψ ϕ and Λb0 → J/ψ Λ using an integrated luminosity of 35 pb^−1 collected in pp collisions at a centre-of-mass energy of 7 TeV by the LHCb experiment. The momentum scale is calibrated with J/ψ → μ+ μ− decays and verified to be known to a relative precision of 2 x 10^−4 using other two-body decays. The results are more precise than previous measurements, particularly in the case of the B0s and Λb0 masses.