D and D-S decay constants from QCD duality at three loops
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# D and D-S decay constants from QCD duality at three loops

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 Bordes Villagrasa, José M.; Peñarrocha Gantes, José Antonio; Schilcher, K. Aquest document és un/a article, creat/da en: 2005 We compute the decay constants of the pseudoscalar mesons D and D_{s} using a linear combination of finite energy sum rules which minimize the contribution of the unknown continuum spectral function. We employ the recent three loop calculation of the pseudoscalar two-point function expanded in powers of the running charm quark mass. The theoretical uncertainties arising from the QCD asymptotic expansion are quite relevant in this case due to the relative small scale of the charm mass. We obtain the following results: f_{D}=177 \pm 21 MeV and f_{D_{s}}=205 \pm 22 MeV. These results, within the error bars, are in good agreement with estimates obtained using Borel transform QCD sum rules, but somewhat smaller than results of recent lattice computations. Bordes Villagrasa, José M. Peñarrocha Gantes, José Antonio Schilcher, K. 2005 D and D-S decay constants from QCD duality at three loops Journal of High Energy Physics 2005 11 014-1 014-13 http://dx.doi.org/10.1088/1126-6708/2005/11/014