NUMERICAL STUDY OF FINITE-TEMPERATURE LATTICE QCD

有限温晶格QCD的数值研究

基本信息

批准号：
10640246
负责人：
UKAWA Akira
金额：
$ 1.73万
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：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640246/
关键词：
QUARK GLUON PLASMA LATTICE QCD FINITE TEMPERATURE FINITE DENSITY LATTICE GAUGE THEORY NUMERICAL SIMULATION HIGH ENERGY HEAVY ION SCATTERING EARLY UNIVERSE クォーク・グルオL・プラズマ量子色力学相転移状態方程式クォークゲルオンプラズマ

项目摘要

This work aimed to elucidate the nature of the phase transition from hadron phase to quark gluon plasma phase, and physical properties of the consequent high temperature phase, using large-scale numerical simulations of quantum chromodynamics on the lattice. In the first year of the project, we investigated the properties of the phase transition itself. In the second and third years of the project, we calculated the equation of state which represent the fundamental information concerning the plasma phase. The main results we have obtained are as follows.1. For understanding the finite-temperature phase transition of the real world, it is very important to learn how the difference of masses of the up and down quark m_<ud> and that of the strange quark m_s affects the nature of the phase transition. We have carried out a systematic determination of the line of phase transition on the (m_<ud>, m_s) plane using the Kogut-Susskind quark action, and identified the critical quark mass beyond … More which the first-order phase transition becomes absent. Further investigation of the SU (3) symmetric case has shown that the end-point of the first-order transition is a second-order transition point, and that the sigma particle becomes massless at that point.2. Past calculations of the equation of state of the quark gluon plasma phase has exclusively used the Kogut-Susskind quark action. In our work we employed the Wilson-type quark action which is far more natural than the Kogut-Susskind quark action in the spin-flavor content. Since this calculation is CPU time intensive, being a full QCD calculation, we have exploited the use of improved actions both for the gluon and quark sectors. We adopted the integral method for calcuation of equation of state. For a methodological preparation, we first calculated the equation of state for pure gauge theory, and determined the temperature dependence of energy density and pressure. Taking the continuum limit, we obtained results for the equation of state which are in agreement with those of the standard plqquette action within 3%. For full QCD, we first determined the phase diagram on the (K,β) plane, identifying the region of parity broken phase and the critical line. We then carried out simulations on lattices with the temporal lattice size N_1=4 and 6 and the spatical size mostly 16^3. The region of quark masses corresponding to m_π/m_ρ=O.6-0.95 were explored, and the energy density and pressure were determined as a function of temperature and quark mass. The main features found in these results are (i) only weak dependence is seen once quark mass falls below m_π/m_ρ=0.9, and (ii) N_1=6 results show an approximate agreement with the continuum Stefan-Boltzmann values above T/ T_1=2. Further studies are needed to confirm and extend these results, in particulr to carry out scaling study using lattices with larger temporal sizes. Less

这项工作旨在阐明使用量子的大规模数值模拟在第一和第一个中，我们研究了量子染色体的大规模数字模拟，我们研究了第二相中的量子。第三个项目呈现有关等离子阶段的基本信息M_ <ud>和奇怪的Quark M_s的性质会影响相变的性质。第一阶透明效量不存在，因为在那个点上，第一阶转变的the the the thew thepoint the the Point rticle在那个点上无质量。 Kogut-sussskind Quark动作比CPU含量的Kogut-susskind Quark动作更为自然。用于纯仪理论的方法论，并与标准的PLQQuetter动作相吻合。平面，Parthen相的区域和临界线。并且能量密度和压力被确定为asatat ure和夸克质量。这些结果中发现的主要特征是（i）仅在M_π/M_π/0.9 ANN值以下的OLLS一次下只能看到一次弱依赖性。 t/ t_1 = 2。需要进一步的研究来确认并扩展这些结果，以较大的时间大小进行缩放研究晶格