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Finite temperature transition in lattice QCD with the strange quark

奇夸克晶格 QCD 中的有限温度跃迁

基本信息

批准号：
07640376
负责人：
KANAYA Kazuyuki
金额：
$ 1.09万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640376/
关键词：
Quantum Chromodynamics finite temperature lattice gauge theory quarks Wilson fermion critical phenomenon improved lattice action numerical simulation クォータ

项目摘要

We study the nature of the finite temperature phase transition of Quantum Chromodynamics (QCD) using the lattice formalism, which allows us nonperturbative investigations with supercomputers. We adopt Wilson fermions for quarks.(1) With the standard lattice action, the nature of finite temperature transitions is studied for the cases of 2,3, and 6 flavors of degenerate quarks and also for the case of massless up and down quarks and a light strange quark. Our simulations indicate that the finite temperature transition in the chiral limit is continuous for two flavors, while it is of first order for 3 and 6 flavors. We find that the transition is of first order for the case of massless up and down quarks and the physical strange quark. This result is different from the previous result with staggered quarks. Since the deviation from the continuum limit is large in both studies on present lattices, a calculation with larger lattice or with an improved action would be needed in order to obt … More ain a definite conclusion about the nature of the QCD transition.(2) The finite temperature transition of QCD with two degenerate light quarks is studied with a renormalization group improved gauge action and the Wilson quark action. It is shown that the chiral condensate satisfies remarkably a scaling relation with the exponents of the three dimensional O (4) Heisenberg model. This indicates that the chiral transition in two-flavor QCD is of second order in the continuum limit.(3) We also investigate the zero temperature phase structure of QCD for flavors from 2 up to 300. Based on numerical results we propose the following picture : When N_F <greater than or equal> 17, there is only a trivial fixed point and therefore the theory in the continuum limit is trivial. On the other hand, when 16 <greater than or equal> N_F <greater than or equal> 7, there is a non-trivial fixed point and therefore the theory is non-trivial with anomalous dimensions, however, without quark confinement. Theories which satisfy both quark confinement and spontaneous chiral symmetry breaking in the continuum limit exist only for N_F <less than Less

我们用格子形式研究了量子色动力学(QCD)有限温度相变的性质，这使得我们可以用超级计算机进行非微扰研究。我们对夸克采用了威尔逊费米子。(1)在标准晶格作用量下，研究了2、3、6种简并夸克以及无质量上下夸克和轻奇异夸克的有限温度跃迁的性质。我们的模拟表明，对于两种口味，手性极限的有限温度转变是连续的，而对于3种和6种口味，有限温度转变是一级的。我们发现，在无质量上下夸克和物理奇异夸克的情况下，跃迁是一级的。这一结果与之前关于交错夸克的结果不同。由于在现有晶格的两种研究中，对连续统极限的偏离都很大，因此需要用更大的晶格或改进的作用量来计算OBT…(2)利用重整化群改进的规范作用和Wilson夸克作用，研究了具有两个简并轻夸克的QCD的有限温度跃迁。结果表明，手性凝聚体与三维O(4)海森堡模型的指数之间存在显著的标度关系。这表明双味QCD的手性跃迁在连续谱极限下是二级的。(3)我们还研究了从2到300种香料的QCD的零温相结构。基于数值结果，我们提出如下图景：当N_F&t；大于或等于-gt；17时，只有一个平凡的不动点，因此连续统极限中的理论是平凡的。另一方面，当16&lt；大于或等于&gt；N_F&lt；大于或等于&gt；7时，存在一个非平凡不动点，因此该理论是具有反常维度的非平凡的，然而，没有夸克禁闭。在连续介质极限中同时满足夸克禁闭和手征对称性自发破缺的理论只存在于N_F&lt；