Measurements of b-hadron lifetimes and effective lifetimes at LHCb

Precision measurements of b-hadron lifetimes are a key goal of the LHCb experiment. In the B0s sector, the measurement of the effective lifetimes for B0s mesons decaying to CP-odd, CP-even and flavour specific final states are essential for constraining the B0s mixing parameters: the width difference ?Gs, the average width Gs and the CP-violating phase fs. Measurements of the effective lifetimes in the decay modes B0s ? J/? f0(980) and B0s ? K+K- are presented, as well as a determination of ?Gs and Gs using the B0s ? J/?f decay mode.