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arXiv 0704.1247hep-phhep-lathep-thnucl-th
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大NC QCD谐振饱和的理性分析

A Rational Approach to Resonance Saturation in large-Nc QCD

P. Masjuan, S. Peris

摘要:

我们指出,QCD中的共振饱和现象可以从Pade近似到亚纯函数的数学理论中得到大Nc极限的理解。这些近似是合理的功能,其中包括任何饱和度与有限数量的共振作为一个特殊的例子,解释了几个结果,出现在文献中。本文利用两点相关器的玩具模型,讨论了Pade近似的主要性质<VV-AA>,特别注意了手征展开、算子乘积展开和共振谱之间的关系。顺便说一句,我们还评论了Migdal在1977年提出的一个旧的建议,该建议最近在AdS/QCD模型的背景下引起了广泛的关注。最后,我们将最简单的Pade近似应用到QCD的<VV-AA>相关器中。一般的结论是,一个合理的逼近可以可靠地描述一个格林函数在欧几里德,但同样是不真实的闵可夫斯基制度,由于外观的非物理极点和/或残留物。

英文摘要:

We point out that resonance saturation in QCD can be understood in the large-Nc limit from the mathematical theory of Pade Approximants to meromorphic functions. These approximants are rational functions which encompass any saturation with a finite number of resonances as a particular example, explaining several results which have appeared in the literature. We review the main properties of Pade Approximants with the help of a toy model for the <VV-AA> two-point correlator, paying particular attention to the relationship among the Chiral Expansion, the Operator Product Expansion and the resonance spectrum. In passing, we also comment on an old proposal made by Migdal in 1977 which has recently attracted much attention in the context of AdS/QCD models. Finally, we apply the simplest Pade Approximant to the <VV-AA> correlator in the real case of QCD. The general conclusion is that a rational approximant may reliably describe a Green's function in the Euclidean, but the same is not true in the Minkowski regime due to the appearance of unphysical poles and/or residues.

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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