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arXiv 0704.2296hep-ph
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在QCD模型中提取手征极限外轻夸克的${\bar q}q$凝聚

Extracting the ${\bar q}q$ condensate for light quarks beyond the chiral limit in models of QCD

R. Williams, C. S. Fischer, M. R. Pennington

摘要:

最近有人提出\cite{Chang:2006bm},通过考虑夸克传播子Schwinger Dyson方程的一类非正定解,可以给出非微扰质量夸克凝聚的可靠而明确的定义。在本文中,我们表明,这个定义是不完整的,不考虑第三类解决方案。事实上,研究这三个类揭示了可能的凝聚定义的简并性,导致整个范围的值。然而,我们表明,{ \it物理}冷凝物实际上可以提取通过简单的拟合的算子乘积展开,这是稳定的考虑三类解决方案一起的程序。我们发现,当前夸克质量的范围从零到25 MeV左右(定义在2 GeV的$\bar{MS}$计划的规模),动态生成的凝聚增加的手征限制在广泛的唯象成功的模型的限制QCD相互作用。最后,第四类节点的解决方案的作用进行了简要讨论。

英文摘要:

It has recently been suggested \cite{Chang:2006bm} that a reliable and unambiguous definition of the non-perturbative massive quark condensate could be provided by considering a non positive-definite class of solutions to the Schwinger Dyson Equation for the quark propagator. In this paper we show that this definition is incomplete without considering a third class of solutions. Indeed, studying these three classes reveals a degeneracy of possible condensate definitions leading to a whole range of values. However, we show that the {\it physical} condensate may in fact be extracted by simple fitting to the Operator Product Expansion, a procedure which is stabilised by considering the three classes of solution together. We find that for current quark masses in the range from zero to 25 MeV or so (defined at a scale of 2 GeV in the $\bar{MS}$ scheme), the dynamically generated condensate increases from the chiral limit in a wide range of phenomenologically successful models of the confining QCD interaction. Lastly, the role of a fourth class of noded solutions is briefly discussed.

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