Abstract
In this article, we recalculate the contributions of all vacuum condensates up to dimension-6, in particular the one-loop corrections to the quark condensates and partial one-loop corrections to the four-quark condensates , in the operator product expansion. Then we study the masses and decay constants of the heavy pseudoscalar mesons D, D s , B and B s using the QCD sum rules with two choices: I we choose the masses by setting m = m(μ) and take perturbative corrections up to the order $ \mathcal{O}\left( {{\alpha_s}} \right) \mathcal{O}\left( {\alpha_s^2} \right) $ and set the energy-scale to be the heavy quark pole mass μ = m Q . In the case of I, the predictions f D = (208 ± 11) MeV and f B = (189 ± 15) MeV are consistent with the experimental data within uncertainties, while the prediction $ {f_{{{D_s}}}}=\left( {241\pm 12} \right) {f_{{{D_s}}}}=\left( {260.0\pm 5.4} \right) $ MeV. In the case of II, the predictions f D = (211 ± 14) MeV, f B = (190 ± 17) MeV, $ {f_{{{D_s}}}}=\left( {258\pm 13} \right) {{{{f_{{{D_s}}}}}} \left/ {{{f_D}}} \right.}=1.22\pm 0.08 $ are all in excellent agreements with the experimental data within uncertainties.