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arXiv 0901.4144hep-thhep-ph
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N=2超对称QCD中Abel与非Abel禁闭的交叉

Crossover between Abelian and non-Abelian confinement in N=2 supersymmetric QCD

M. Shifman, A. Yung

摘要:

在本文中,我们调查的性质转变从阿贝尔限制到非阿贝尔限制(即交叉与相变)。为此,我们考虑了N=2的基本模型,其中首次发现了非阿贝尔通量管(弦):具有U(N)规范群和N_f=N味基本物质(夸克)的超对称QCD。Fayet-Iliopoulos项的引入触发了夸克凝聚,并导致了非阿贝尔弦的形成。在这个模型中有两个可调参数:夸克质量差和夸克质量差Δm。我们得到了(ε,Δm)平面上的相图。在大ε和小Δm时,弦取向模量的世界片动力学可用N=2的二维CP(N-1)模型描述.我们表明,当我们减少的理论表现出交叉的阿贝尔(Seiberg-Witten)政权。现在,在低能谱中只有N个自由度,而不是非阿贝尔理论中的N^2个自由度。具有一定量子数的双子凝聚形成阿贝尔Z_N弦,其通量固定在规范群的Cartan子代数中。当我们增加N时,这种交叉变得非常尖锐,在N = \infty处变成真正的相变。

英文摘要:

In this paper we investigate the nature of the transition from Abelian to non-Abelian confinement (i.e. crossover vs. phase transition). To this end we consider the basic N=2 model where non-Abelian flux tubes (strings) were first found: supersymmetric QCD with the U(N) gauge group and N_f=N flavors of fundamental matter (quarks). The Fayet-Iliopoulos term ξtriggers the squark condensation and leads to the formation of non-Abelian strings. There are two adjustable parameters in this model: ξand the quark mass difference Δm. We obtain the phase diagram on the (ξ, Δm) plane. At large ξand small Δm the world-sheet dynamics of the string orientational moduli is described by N=2 two-dimensional CP(N-1) model. We show that as we reduce ξthe theory exhibits a crossover to the Abelian (Seiberg-Witten) regime. Instead of N^2 degrees of freedom of non-Abelian theory now only N degrees of freedom survive in the low-energy spectrum. Dyons with certain quantum numbers condense leading to the formation of the Abelian Z_N strings whose fluxes are fixed inside the Cartan subalgebra of the gauge group. As we increase N this crossover becomes exceedingly sharper becoming a genuine phase transition at N =\infty.

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