Measurement of b hadron lifetimes in pp collisions at CMS

Abstract

Precise measurements of the lifetimes of the B0, B0s, Λ0b, and B+c hadrons using the decay channels B0 → J/ψK∗(892)0, B0 → J/ψKs0, B0s → J/ψπ+π−, B0s → J/ψφ(1020), Λ0b → J/ψΛ0, and B+c → J/ψπ+were performed. The data sample, corresponding to an integrated luminosity of 19.7 fb−1, was collected by the CMS detector at the LHC in proton-proton collisions at s = 8 TeV. The B0 lifetime is measured to be 453.0 ± 1.6(stat) ± 1.5(syst) µm in J/ψK∗(892)0 and 457.8 ±2.7(stat) ±2.7(syst) µm in J/ψKs0. The effective lifetime of the B0s 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: cτB0s →J/ψπ+π− = 502.7 ± 10.2(stat) ± 3.2(syst) µm and cτB0s →J/ψφ(1020) = 443.9 ± 2.0(stat) ± 1.2(syst) µm. The Λ0b lifetime is found to be 442.9 ± 8.2(stat) ± 2.7(syst) µm. 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+ to reduce the systematic uncertainty, is 162.3 ±8.2(stat) ±4.7(syst) ±0.1 (τB+) µm. All results are in agreement with current world-average values.