We address the issue of the quark-hadron duality in the spectral densities induced by the heavy-light quark currents Q̄q. In the limit mQ → ∞, mq → 0 we observe an enhancement of the physical spectral density compared to the quark one in the scalar and axial channels, due to the Goldstone meson contributions. This may imply that the scale where duality sets in is higher in these channels than in the vector (pseudoscalar) case. Implications for the non-leptonic decays of B mesons (the b → c̄cs transition) are considered. We discuss in detail the decay pattern and obtain an independent estimate of the "wrong"-sign D yield.
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The authorsw ouldlike to thankG . Altarelli,E Ball, I. Bigi and J. Rosnerf or useful discussionsT,. Browderf or commentosn the experimentsailt uationO. neof the authors (B.B.) thanksI. Dunietzf or explaininhgi s resultsT. his work was supporteidn part by DOE undert he grant numberD E-FG02-94ER4082b3y, NSF undert he grantn umber PHY 92-13313a ndby the Israel Academyo f Sciencesa ndthe VPR Technionfu nd.