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arXiv 0911.2696hep-lathep-phhep-th
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周期边界条件下伴随费米子的PNJL模型

A PNJL Model for Adjoint Fermions with Periodic Boundary Conditions

Hiromichi Nishimura, Michael C. Ogilvie

备注：
13 pages, 7 figures
发表信息：
Phys.Rev.D81:014018,2010
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摘要：

最近在类QCD理论方面的工作表明，在$R^{3}\times S^{1}$的规范理论中加入服从周期边界条件的伴随费米子，可以恢复$S^{1}$的足够小周长$L$的中心对称性和禁闭。在小的$L$，微扰理论可以可靠地用于计算在紧凑方向上的Polyakov环$P$的有效势。周期性伴随费米子的作用与规范场相反，这本身会导致在小$L$处的去精细相位。为了使费米子效应在有效势中支配规范场效应，费米子质量必须足够小。这表明，手征对称性破缺效应是潜在的重要。我们发展了一个Polyakov-Nambu-JonaLasinio（PNJL）模型，它结合了伴随QCD模型在小$L$处的已知微扰行为和手征对称性破缺效应，产生了Polyakov环$P$和手征序参量$\barψψ$的有效势.富相结构从有效势中出现。我们的研究结果是一致的，最近的晶格模拟Cossu和D 'Elia，没有发现证据之间的直接连接的小- $L$和大- $L$限制区域。然而，如果考虑一个不相关的四费米子相互作用的扩展场论模型，这两个受限区域是间接连接的。因此，小- $L$和大- $L$区域是单个受限相的一部分。

英文摘要：

Recent work on QCD-like theories has shown that the addition of adjoint fermions obeying periodic boundary conditions to gauge theories on $R^{3}\times S^{1}$ can lead to a restoration of center symmetry and confinement for sufficiently small circumference $L$ of $S^{1}$. At small $L$, perturbation theory may be used reliably to compute the effective potential for the Polyakov loop $P$ in the compact direction. Periodic adjoint fermions act in opposition to the gauge fields, which by themselves would lead to a deconfined phase at small $L$. In order for the fermionic effects to dominate gauge field effects in the effective potential, the fermion mass must be sufficiently small. This indicates that chiral symmetry breaking effects are potentially important. We develop a Polyakov-Nambu-Jona Lasinio (PNJL) model which combines the known perturbative behavior of adjoint QCD models at small $L$ with chiral symmetry breaking effects to produce an effective potential for the Polyakov loop $P$ and the chiral order parameter $\barψψ$. A rich phase structure emerges from the effective potential. Our results are consistent with the recent lattice simulations of Cossu and D'Elia, which found no evidence for a direct connection between the small-$L$ and large-$L$ confining regions. Nevertheless, the two confined regions are connected indirectly if an extended field theory model with an irrelevant four-fermion interaction is considered. Thus the small-$L$ and large-$L$ regions are part of a single confined phase.

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