Spectator effects and lifetimes of heavy hadrons
  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. 
Fabrizio Gabbiani, Andrei I. Onishchenko, and Alexey A. Petrov