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arXiv 0906.3941hep-lathep-ph
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猝灭格点量子色动力学中有限温度有限动量的夸克传播子

Quark propagator at finite temperature and finite momentum in quenched lattice QCD

Frithjof Karsch, Masakiyo Kitazawa

摘要:

本文利用Clover改进的Wilson费米子在Landau规范下分析了猝灭格点量子色动力学中零动量和非零动量时在临界温度上下的夸克谱函数。结果表明,在临界温度附近的退禁闭相中,时间夸克关联函数可以用谱函数的双极近似很好地再现。这表明夸克场的激发模式具有小的衰减率。利用该方法分析了谱函数对裸夸克质量和动量的依赖性。在手征极限下,我们发现夸克谱函数有两个集体模,分别对应于高温极限下的正常激发和等离子体激发。在一个相当宽的温度范围内,在退禁闭阶段的极质量,这些模式在零动量,这对应于夸克的热质量,是近似成比例的温度。随着裸夸克质量的增加,等离子体模逐渐消失,谱函数由单极主导。我们还讨论了重夸克在退禁闭相中的准粒子性质。在约束相,发现谱函数的极点分析完全失效。

英文摘要:

We present an analysis of the quark spectral function above and below the critical temperature for deconfinement performed at zero and non-zero momentum in quenched lattice QCD using clover improved Wilson fermions in Landau gauge. It is found that the temporal quark correlation function in the deconfined phase near the critical temperature is well reproduced by a two-pole ansatz for the spectral function. This indicates that excitation modes of the quark field have small decay rates. The bare quark mass and momentum dependence of the spectral function is analyzed with this ansatz. In the chiral limit we find that the quark spectral function has two collective modes corresponding to the normal and plasmino excitations in the high temperature limit. Over a rather wide temperature range in the deconfined phase the pole mass of these modes at zero momentum, which corresponds to the thermal mass of the quark, is approximately proportional to temperature. With increasing bare quark masses the plasmino mode gradually disappears and the spectral function is dominated by a single pole. We also discuss quasi-particle properties of heavy quarks in the deconfined phase. In the confined phase, it is found that the pole ansatz for the spectral function fails completely.

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