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

我们使用晶格形式研究了量子色动力学（QCD）的有限温度相变的本质，这使得我们能够使用超级计算机进行非微扰研究。我们采用威尔逊费米子来描述夸克。（1）通过标准晶格作用，有限温度的本质。研究了 2,3 和 6 种简并夸克的情况以及无质量的上夸克和下夸克的情况以及我们的模拟表明，手性极限中的有限温度跃迁对于两种风味是连续的，而对于 3 种和 6 种风味来说，它是一阶的。我们发现，对于无质量的情况，该转变是一阶的。下夸克和物理奇夸克的结果与之前交错夸克的结果不同，因为在现有晶格、更大晶格或改进的计算中与连续统极限的偏差都很大。为了获得关于 QCD 跃迁性质的明确结论，需要采取行动。(2) 利用重正化群改进的规范作用和威尔逊夸克作用，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)海森堡模型的指数满足异常的比例关系，这表明双味QCD中的手性跃迁是第二次的。 (3) 我们还研究了从 2 到 300 口味的 QCD 零温相结构。根据数值结果，我们提出了下图：当 N_F <大于或等于> 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 <大于或等于> N_F <大于或等于> 7 时，存在一个。非平凡不动点，因此该理论对于反常维度来说是非平凡的，但是，在没有夸克禁闭的情况下，满足夸克禁闭和连续统极限中自发手性对称性破缺的理论仅存在于 N_F < 小于 Less 的情况下。