Measurements of the $B^+$, $B^0$, $B_s^0$ meson and $Λ_b^0$ baryon lifetimes

Abstract

Measurements of $b$-hadron lifetimes are reported using $pp$ collision data, corresponding to an integrated luminosity of 1.0fb$^{-1}$, collected by the LHCb detector at a centre-of-mass energy of $7$Tev. Using the exclusive decays $B^+\to J/ψK^+$, $B^0\to J/ψK^*(892)^0$, $B^0\to J/ψK^0_{\rm S}$, $Λ_b^0\to J/ψΛ$ and $B^0_s\to J/ψϕ$ the average decay times in these modes are measured to be $τ_{B^+\to J/ψK^+}$ = $1.637 \pm$ 0.004 $\pm$ 0.003 ps, $τ_{B^0\to J/ψK^*(892)^0}$ = $1.524 \pm$ 0.006 $\pm$ 0.004 ps, $τ_{B^0\to J/ψK^0_{\rm S}}$ = $1.499 \pm$ 0.013 $\pm$ 0.005 ps, $τ_{Λ_b^0\to J/ψΛ}$ = $1.415 \pm$ 0.027 $\pm$ 0.006 ps and $τ_{B^0_s\to J/ψϕ}$ = $1.480 \pm$ 0.011 $\pm$ 0.005 ps, where the first uncertainty is statistical and the second is systematic. These represent the most precise lifetime measurements in these decay modes. In addition, ratios of these lifetimes, and the ratio of the decay-width difference, $ΔΓ_d$, to the average width, $Γ_d$, in the $B^0$ system, $ΔΓ_d/Γ_d = -0.044 \pm 0.025 \pm 0.011$, are reported. All quantities are found to be consistent with Standard Model expectations.

28 pages, 4 figures. Updated references