Dₛ Lifetime, mb, mc and |Vcb| in the Heavy Quark Expansion

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We present some straightforward applications of the QCD heavy quark expansion, stated in previous papers [1-3], to the inclusive widths of heavy flavour hadrons. We address the question of the Dₛ lifetime and argue that -- barring Weak Annihilation (WA) -- τ(Dₛ) is expected to exceed τ(D⁰) by several percent; on the other hand WA could provide a difference of up to 1020% of any sign. We extract mc, mb and |Vcb| from ΓSL(D+) and ΓSL(B). The values of the quark masses are somewhat higher, but compatible with estimates from QCD sum rules; we obtain |Vcb|≃ 0.043 for τ(B)=1.4 psec and BRSL(B)=10.5%. We discuss the associated uncertainties in the 1/mQ expansion as well as some consequences for other electroweak decays.