Measurement of b hadron lifetimes in pp collisions at √s = 8 TeV

Measurements are presented of the lifetimes of the B^0, B^0_ s, Λ^0_b, and B+_c hadrons using the decay channels B^0→J/ψK∗(892)^0, B^0→J/ψK^0_S, B^0_s→J/ψπ^+π^−, B^0_s→J/ψϕ(1020), Λ^0_b→J/ψΛ^0, and B+_c→J/ψπ^+. The data sample, corresponding to an integrated luminosity of 19.7fb^(-1), was collected by the CMS detector at the LHC in proton–proton collisions at √s = 8 TeV. The B^0 lifetime is measured to be 453.0 ± 1.6(stat) ± 1.8(syst) μ m in J/ψK∗(892)^0 and 457.8 ± 2.7(stat) ± 2.8(syst) μ m in J/ψK^0_S, which results in a combined measurement of cτ_(B^0) = 454.1 ± 1.4(stat) ± 1.7(syst) μ m. The effective lifetime of the B^0_s meson is measured in two decay modes, with contributions from different amounts of the heavy and light eigenstates. This results in two different measured lifetimes: cτ_(B^0_s) → J/ψπ^+π^− = 502.7 ± 10.2(stat) ± 3.4(syst) μ m and cτ_(B^0_s) → J/ψϕ(1020) = 443.9 ± 2.0(stat) ± 1.5(syst) μ m. The Λ^0_b lifetime is found to be 442.9 ± 8.2(stat) ± 2.8(syst) μ m. The precision from each of these channels is as good as or better than previous measurements. The B+_c lifetime, measured with respect to the B+B+ to reduce the systematic uncertainty, is 162.3 ± 7.8(stat) ± 4.2(syst) ± 0.1(τ_(B+)) μ m. All results are in agreement with current world-average values.