We present a calculation of subleading $1/m_b$ corrections to spectator effects in the ratios of beauty hadron lifetimes in heavy-quark expansion. 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 ${\Lambda }_b$ baryon and $B_d$ meson. We obtain $\tau (B_u)/\tau (B_d)=1.06\pm 0.02$, $\tau (B_s)/\tau (B_d)=1.00\pm 0.01$, $\tau ({\Lambda }_b)/\tau (B_d)=0.86\pm 0.05$.

• Received 22 July 2004

DOI:https://doi.org/10.1103/PhysRevD.70.094031