Lifetime ratios of beauty hadrons at the next-to-leading order in QCD

We compute the next-to-leading order QCD corrections to spectator effects in the lifetime ratios of beauty hadrons. With respect to previous calculations, we take into account the non-vanishing value of the charm quark mass. We obtain the predictions tau (B+)/tau(B-d) = 1.06+/-0.02, tau(B-s)/tau(B-d) = 1.00+/-0.0 1 and tau(Lambda(b))/tau(B-d) = 0.90+/-0.05, in good agreement with the experimental results. In the case of tau(B-s)/tau(B-d) and tau(Lambda(b))/tau(B-d), however, some contributions, which either vanish in the vacuum insertion approximation or represent a pure NLO correction, have not been determined yet. (C) 2002 Elsevier Science B.V. All rights reserved