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

Authors

• CMS Collaboration, CMS CollaborationFollow

Document Type

Article

Date of this Version

2018

Citation

Eur. Phys. J. C (2018) 78:457

Comments

© CERN for the benefit of the CMS collaboration 2018

https://doi.org/10.1140/epjc/s10052-018-5929-3

Abstract

Measurements are presented of the lifetimes of the B⁰, B_s^0 , Λ_b^0 , and B_c^+ hadrons using the decay channels B⁰ → J/ψK^∗ (892)⁰, B⁰ → J/ψK_S^0 , B_s^0 → J/ψπ + π −, B_s^0 →J/ψφ(1020), Λ_b^0 →J/ψΛ⁰, and B_c^+ →J/ψπ⁺. 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 = 8TeV. The B⁰ lifetime is measured to be 453.0 ± 1.6 (stat) ± 1.8 (syst) μm in J/ψK^∗ (892)⁰ and 457.8 ± 2.7 (stat) ± 2.8 (syst)μm in J/ψK_S^0, which results in a combined measurement of cτ_B⁰ = 454.1 ± 1.4 (stat) ± 1.7 (syst)μm. The effective lifetime of the B_s^0 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_s^0} →J/ψπ + π⁻ = 502.7 ± 10.2 (stat) ± 3.4 (syst)μm and cτ_{B_s^0} →J/ψφ(1020) = 443.9 ± 2.0 (stat) ± 1.5 (syst)μm. The Λ_b^0 lifetime is found to be 442.9 ± 8.2 (stat) ± 2.8 (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 ± 7.8 (stat) ± 4.2 (syst) ± 0.1 (τ_B⁺)μm. All results are in agreement with current world-average values.