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arXiv 1008.3129hep-ph
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由QCD求和规则计算重介子衰变常数

Heavy-meson decay constants from QCD sum rules

Wolfgang Lucha, Dmitri Melikhov, Silvano Simula

摘要:

本文给出了最近从重-轻赝标流两点关联器中提取重赝标介子D、D_s、B和B_s衰变常数的求和规则[1]。我们的主要重点在于控制所有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。获得这种控制已成为可能的应用程序,我们的新程序提取强子可观的双阈值依赖于Borel参数的基础上。对于粲介子衰变常数,f_D=206.2 \pm 7.3(OPE)\pm 5.1(syst)MeV,f_Ds=245.3 \pm 15.7(OPE)\pm 4.5(syst)MeV.对于美介子,衰变常数对b夸克的MSbar质量mb(mb)的精确值非常敏感。通过要求我们的求和规则估计与f_B的晶格测定的平均值相匹配,我们提取出相当精确的值mb(mb)=(4.245 \pm 0.025)GeV。将这个参数值输入我们的求和规则公式,得到美介子衰变常数f_B = 193.4 \pm 12.3(OPE)\pm 4.3(syst)MeV,f_Bs =232.5 \pm 18.6(OPE)\pm 2.4(syst)MeV。

英文摘要:

We sketch a recent sum-rule extraction of the decay constants of the heavy pseudoscalar mesons D, D_s, B, and B_s from the two-point correlator of heavy-light pseudoscalar currents [1]. Our main emphasis lies on the control over all the uncertainties in the decay constants, related both to the input QCD parameters and to the limited accuracy of the method of sum rules. Gaining this control has become possible by application of our new procedure of extracting hadron observables based on a dual threshold depending on the Borel parameter. For the charmed-meson decay constants, we find f_D=206.2\pm 7.3(OPE) \pm 5.1(syst) MeV, f_Ds=245.3\pm 15.7(OPE) \pm 4.5(syst) MeV. For the beauty mesons, the decay constants turn out to be extremely sensitive to the precise value of the MSbar mass of the b-quark, mb(mb). By requiring our sum-rule estimate to match the average of the lattice determinations of f_B, we extract the rather accurate value mb(mb)=(4.245\pm 0.025) GeV. Feeding this parameter value into our sum-rule formalism leads to the beauty-meson decay constants f_B = 193.4 \pm 12.3(OPE) \pm 4.3(syst) MeV, f_Bs =232.5 \pm 18.6(OPE) \pm 2.4(syst) MeV.

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