Measurement of $B^{0}_{s}$ and $D^{-}_{s}$ meson lifetimes

Abstract

We report on a measurement of the flavor-specific $B^{0}_{s}$ lifetime and of the $D^{-}_{s}$ lifetime using proton-proton collisions at center-of-mass energies of 7 and 8 TeV, collected by the LHCb experiment and corresponding to 3.0 fb$^{-1}$ of integrated luminosity. Approximately 407 000 $B^{0}_{s} \rightarrow D^{(*)-}_{s} μ^{+}ν_μ$ decays are partially reconstructed in the $K^{+}K^{-}π^{-}μ^{+}$ final state. The $B^{0}_{s}$ and $D^{-}_{s}$ natural widths are determined using, as a reference, kinematically similar $B^{0} \rightarrow D^{(*)-}μ^{+}ν_μ$ decays reconstructed in the same final state. The resulting differences between widths of $B^{0}_{s}$ and $B^{0}$ mesons and of $D^{-}_{s}$ and $D^{-}$ mesons are $Δ_Γ(B) =-0.0115 \pm 0.0053 (stat) \pm 0.0041 (syst)$ ps$^{-1}$ and $Δ_Γ(D) = 1.0131 \pm 0.0117 (stat) \pm 0.0065 (syst)$ ps$^{-1}$, respectively. Combined with the known $B^{0}$ and $D^{-}$ lifetimes, these yield the flavor-specific $B^{0}_{s}$ lifetime, $τ^{\rm fs}_{B^{0}_{s}} = 1.547 \pm 0.013 (stat) \pm 0.010 (syst) \pm 0.004 (τ_{B})$ ps and the $D^{-}_{s}$ lifetime, $τ_{D^{-}_{s}} = 0.5064 \pm 0.0030 (stat) \pm 0.0017 (syst) \pm 0.0017 (τ_{D})$ ps The last uncertainties originate from the limited knowledge of the $B^0$ and $D^{-}$ lifetimes. The results improve upon current determinations.

16 pages, 8 figures. Minor editorial changes to match the published version. All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2017-004.html