Precision measurements of b hadron lifetimes at LHCb

Precision lifetime measurements of $B^+, B^0$ and $B^0_s$ mesons and the $\Lambda^0_b$ baryon are presented. The hadrons are required to decay into a final state containing a $J/\psi$ resonance. The used dataset represents an integrated luminosity of 1 fb$^{-1}$. The average decay times are measured to be $\tau_{B^+ \to J/\psi K^+} = 1.637 \pm 0.004 \pm 0.003$ ps, $\tau_{B^0 \to J/\psi K^{*0}}= 1.524 \pm 0.006 \pm 0.004$ ps, $\tau_{B^0 \to J/\psi K^0_s} = 1.499 \pm 0.013 \pm 0.005$ ps, $\tau_{\Lambda^0_b \to J/\psi \Lambda} = 1.415 \pm 0.027 \pm 0.006$ ps and $\tau_{B^0_s \to J/\psi \phi} = 1.480 \pm 0.011 \pm 0.005$ ps, where the first uncertainty is statistical and the second systematic. Furthermore lifetime ratios are determined.