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arXiv 1203.6897hep-ph
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具有高动量扰动QCD行为的扩展解析QCD模型

Extended analytic QCD model with perturbative QCD behavior at high momenta

César Ayala, Carlos Contreras, Gorazd Cvetič

备注：
15 pages, 6 figures; in v2 Sec.IV is extended after Eq.(48) and refs.[51-52] added; v2 published in Phys.Rev.D85,114043(2012)
发表信息：
Phys.Rev.D85,114043(2012)
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摘要：

与微扰QCD相比，解析QCD模型具有运行耦合，其解析性质正确地反映了类空观测量的解析性质。预计这种运行耦合的不连续（谱）函数在类时动量较大时与微扰情况一致;然而，在类时动量较低时，情况尚不清楚。在后一种情况下，我们将谱函数的未知行为参数化为（两个）δ函数的总和;而谱函数的微扰行为的开始被设置为1.0-1.5 GeV。这与文献中用于模拟强子谱函数的“最小强子反子”非常相似。对于运行耦合本身，我们施加的条件，它基本上合并与高类空动量的微扰耦合。此外，我们还要求模型能再现测量良好的非奇异半强子（V+A）τ衰变比值。因此，我们得到了一个QCD框架，它基本上是不可区分的微扰QCD在高动量（Q > 1 GeV），并在低动量它尊重的基本解析性质的类空观测所规定的一般原则的局域量子场论。

英文摘要：

In contrast to perturbative QCD, the analytic QCD models have running coupling whose analytic properties correctly mirror those of spacelike observables. The discontinuity (spectral) function of such running coupling is expected to agree with the perturbative case at large timelike momenta; however, at low timelike momenta it is not known. In the latter regime, we parametrize the unknown behavior of the spectral function as a sum of (two) delta functions; while the onset of the perturbative behavior of the spectral function is set to be 1.0-1.5 GeV. This is in close analogy with the "minimal hadronic ansatz" used in the literature for modeling spectral functions of correlators. For the running coupling itself, we impose the condition that it basically merges with the perturbative coupling at high spacelike momenta. In addition, we require that the well-measured nonstrange semihadronic (V+A) tau decay ratio value be reproduced by the model. We thus obtain a QCD framework which is basically indistinguishable from perturbative QCD at high momenta (Q > 1 GeV), and at low momenta it respects the basic analyticity properties of spacelike observables as dictated by the general principles of the local quantum field theories.

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