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arXiv 1008.2698hep-ph
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用QCD求和规则计算重赝标介子的衰变常数

Decay constants of heavy pseudoscalar mesons from QCD sum rules

Wolfgang Lucha, Dmitri Melikhov, Silvano Simula

摘要:

我们重新审视了从重-轻赝标流的两点相关器中提取D、Ds、B和Bs介子衰变常数的求和规则。我们使用算子乘积展开的MSbar重夸克质量表示的相关,微扰展开表现出合理的收敛。我们的主要重点放在控制的不确定性的衰减常数,既涉及到输入QCD参数和有限的精度的求和规则的方法。这成为可能,由于我们的程序提取强子可观的,涉及作为新的功能双阈值取决于Borel参数的应用程序。对于粲介子,我们得到衰变常数f_D=206.2 \pm 7.3(OPE)\pm 5.1(syst)MeV和f_Ds=245.3 \pm 15.7(OPE)\pm 4.5(syst)MeV.对于美介子,衰变常数对mb(mb)的精确值非常敏感。通过要求我们的求和规则估计匹配f_B的晶格结果的平均值,提取了非常精确的值mb(mb)=4.245 \pm 0.025 GeV,得到f_B=193.4 \pm 12.3(OPE)\pm 4.3(syst)MeV和f_Bs=232.5 \pm 18.6(OPE)\pm 2.4(系统)MeV。

英文摘要:

We revisit the sum-rule extraction of the decay constants of the D, Ds, B, and Bs mesons from the two-point correlator of heavy-light pseudoscalar currents. We use the operator product expansion for this correlator expressed in terms of the MSbar heavy-quark mass, for which the perturbative expansion exhibits a reasonable convergence. Our main emphasis is laid on the control over the uncertainties in the decay constants, related both to the input QCD parameters and to the limited accuracy of the method of sum-rules. This becomes possible due to the application of our procedure of extracting hadron observables that involves as novel feature dual thresholds depending on the Borel parameter. For charmed mesons, we find the decay constants f_D=206.2\pm 7.3(OPE)\pm 5.1(syst) MeV and f_Ds=245.3\pm 15.7(OPE)\pm 4.5(syst) MeV. For beauty mesons, the decay constants turn out to be extremely sensitive to the precise value of mb(mb). By requiring our sum-rule estimate to match the average of the lattice results for f_B, a very accurate value mb(mb)=4.245\pm 0.025 GeV is extracted, leading to f_B=193.4\pm 12.3(OPE)\pm 4.3(syst) MeV and f_Bs=232.5\pm 18.6(OPE)\pm 2.4(syst) MeV.

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