Measurements of B lifetimes at LHCb

Measurements of the $B_s^0$ effective lifetime in decays to CP-odd and CP-even flavour specific final states allow to probe the width difference $\mathrm{\Delta }{\mathrm{\Gamma }}_s$ and the CP-violating phase ${\varphi }_s$ of $B_s^0-{\bar{B}}_s^0$ mixing box-diagram. Measurements of the effective lifetime in the decay channels $B_s^0\to K^{+}{K}^{-}$ and $\bar{B}_s^0 \rightarrow J/\psi f_0(980)$arepresented,aswellasameasurementof$\Delta \Gamma_s$and$\Gamma_s$performedbyataggedtime-dependentangularanalysisof$B_s^0 \rightarrow J/\psi \phi$decaysandameasurementofthesignof$\Delta \Gamma_s$, using data collected during 2011 with the LHCb detector.