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arXiv 1111.5411hep-phnucl-th
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推广的非定域手征夸克模型计算D介子和B介子弱衰变常数

Extended nonlocal chiral-quark model for the D- and B-meson weak-decay constants

Seung-il Nam

摘要:

本文建立了由(u,d,c,b)夸克组成的重轻夸克系统的唯象有效模型,即扩展的非定域手征夸克模型(ExNLChQM),用于计算重介子弱衰变常数f_D和f_B。ExNLChQM是基于重夸克有效场论和稀瞬子真空组态的。在ExNLChQM中,一部分重介子质量被认为是由非平凡的QCD真空贡献产生的,这与通常的瞬子方法中的轻夸克相似。因此,有效的重夸克和轻夸克质量变得依赖于动量,并扮演着平滑的紫外调节器的角色。采用ExNLChQM的有效作用量的一般外场方法,根据不同的模型参数,我们得到了fD =(169.28 ~ 234.57)MeV和fB =(165.41 ~ 229.21)MeV。这些值与实验数据和各种理论估计比较吻合。我们还讨论了重夸克对QCD真空的影响,以及根据重夸克自旋对称性得到的衰变常数f_D^* 和f_B^*。

英文摘要:

In this work, we construct a phenomenological effective model for the heavy-light quark systems, which consist of (u,d,c,b) quarks, i.e. extended nonlocal chiral-quark model (ExNLChQM) to compute the heavy-meson weak-decay constants f_D and f_B. ExNLChQM is based on the heavy-quark effective field theory as well as the dilute instanton-vacuum configuration. In ExNLChQM, a certain portion of the heavy-meson mass is considered to be generated from the nontrivial QCD vacuum contribution, being similar to that for the light quarks in usual instanton approaches. Hence, the effective heavy- and light-quark masses become momentum-dependent and play the role of a smooth UV regulator. Employing a generic external-field method applied to the effective action from ExNLChQM, we obtain f_D = (169.28 ~ 234.57) MeV and f_B = (165.41 ~ 229.21) MeV from the numerical results, depending on different model parameters. These values are in relatively good agreement with experimental data and various theoretical estimations. We also discuss the heavy-quark effects on the QCD vacuum, and the decay constants f_D^* and f_B^* in terms of the heavy-quark spin symmetry.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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