Lifetimes of Heavy Hadrons *

We review current status of theoretical predictions of lifetimes of heavy hadrons in heavy-quark expansion. We present a calculation of subleading 1/m b corrections to spectator effects in the ratios of beauty hadron lifetimes. We find that these effects are sizable and should be taken into account in systematic analyses of heavy hadron lifetimes. In particular, the inclusion of 1/m b corrections brings into agreement the theoretical predictions and experimental observations of the ratio of lifetimes of Λ b-baryon and B d meson. We obtain τ (Bu)/τ (B d) = 1.09 ± 0.03, τ (Bs)/τ (B d) = 1.00 ± 0.01, τ (Λ b)/τ (B d) = 0.87 ± 0.05.