Phenomenological analysis of D meson lifetimes - art. no. 014008

The QCD-based operator-product-expansion technique is systematically applie d to the study of charmed meson lifetimes. We stress that it is crucial to take into account the momentum of the spectator light quark of charmed meso ns: otherwise the destructive Pauli-interference effect in D+ decays will l end to a negative decay width for the D+. We have applied the QCD sum rule approach to estimate the hadronic matrix elements of color-singlet and colo r-octet 4-quark operators relevant to nonleptonic inclusive D decays. The l ifetime of D-s(+) is found to be longer than that of D-o because the latter receives a constructive W-exchange contribution, whereas the hadronic anni hilation and leptonic contributions to the former are compensated by the Pa uli interference. We obtain the lifetime ratio tau(D-s(+))/tau(D-o) approxi mate to 1.08 +/- 0.04, which is larger than some earlier theoretical estima tes, but still smaller than the recent measurements by CLEO and E791.