QCD and other models at finite density, Stochastic Quantisation, Non-equilibriumphenomena in Quantum Field Theories.

有限密度下的 QCD 和其他模型、随机量化、量子场论中的非平衡现象。

• 批准号: 203063162
• 负责人: Professor Dr. Ion Olimpiu Stamatescu
• 金额: --
• 依托单位: Max-Planck-Institut für Physik (Werner-Heisenberg-Institut)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/203063162?language=en
• 关键词: QCD; other; models; finite; density

In the Standard Modell the nuclear forces are described by Quantum Chromodynamics (QCD). The seminal proposal of K. Wilson [1] from 1974 to realise this theory on a discretized euclidean space-time, and the pioneering work of M. Creutz [2] on Monte Carlo simulations led in the following decades to quantitative results from first principles reproducing the experimental data and thus providing the basis for our trust in this theory. Another simulation method, based on the Langevin equation, has also been followed [3-5].Some physically relevant questions were however not accessible - such as heavy ion collisions and super-dense stars, or dynamical processes in real time and non-equilibrium situations. In all these cases the path integral involves a complex action and numerical methods based on a positive weighting of the configurations could not be applied. The complex Langevin (CL) method, proposed long ago by G. Parisi [6] and J. Klauder [7] allows in principle to overcome these limitations [5] and was applied to lattice models [8-10]. However the method remained slightly suspect, since in some cases it would lead to clearly incorrect results [11,12] and there was no serios attempt to further develop it. Only recently, with the rising of outstanding physical questions this method found again interest, following the proposals to apply it to dynamical real time processes by J. Berges and I.-O. Stamatescu [13] as well as to QCD at non-zero chemical potential by G. Aarts and I.-O. Stamatescu [14].The peculiarities of this method follow from the complexification of the variable space, in particular the formal proof for correct convergence depends on additional conditions [15]. In our analysis until now we have followed theoretical questions concerning the method, and its application to realistic models. We have established quantitative criteria to ensure correct convergence and developed procedures to improve the properties of the simulations decisively [16-19]. This made the application to QCD-related models [20-23] and to full QCD [24,25] possibble.Based on these results we now want to attack precision questions concerning outstanding physical problems, besides further methodological analyses. Concerning QCD at non-zero density the aim is to expand the region of parameters in which reliable data can be obtained and to draw the phase diagram in the temperature-chemical potential plane. Especially reaching low temperatures is an important task for approaching such questions as the behaviour of super-dense matter.Moreover we want to address now questions which we could not pursue in the first part of the project, namely dynamical processes in real time. Here also the aims of the analysis will be the extension of the parameter region and of the application to new, realistic models.The citations refer to the Bibliography included in the application.

在标准模型中，核力由量子色动力学（QCD）描述。K. Wilson [1]在离散欧氏时空上实现了这一理论，M. Creutz [2]在蒙特卡罗模拟上的研究在接下来的几十年里导致了第一性原理的定量结果，重现了实验数据，从而为我们对这个理论的信任提供了基础。另一种基于朗之万方程的模拟方法也被采用[3-5]。然而，一些物理相关的问题是无法实现的-例如重离子碰撞和超密度恒星，或者真实的时间和非平衡情况下的动力学过程。在所有这些情况下的路径积分涉及一个复杂的行动和数值方法的基础上的一个积极的加权的配置不能应用。本文介绍了G. Parisi [6]和J. Klauder [7]原则上允许克服这些限制[5]，并应用于晶格模型[8-10]。然而，该方法仍然有点可疑，因为在某些情况下，它会导致明显不正确的结果[11，12]，并没有serios尝试进一步发展它。只是最近，随着突出的物理问题的出现，这种方法再次发现兴趣，以下建议将其应用于动态真实的时间过程由J. Berges和I. O. Stamatescu [13]以及G.我和阿特- O. Stamatescu [14]。这种方法的特点来自变量空间的复杂化，特别是正确收敛的形式证明取决于附加条件[15]。到目前为止，在我们的分析中，我们一直在关注与该方法有关的理论问题，以及它在现实模型中的应用。我们已经建立了定量标准，以确保正确的收敛和开发程序，以改善性能的模拟果断[16-19]。这使得应用于QCD相关模型[20-23]和完全QCD [24，25]成为可能。基于这些结果，我们现在除了进一步的方法分析外，还想解决有关突出物理问题的精度问题。关于非零密度下的QCD，目的是扩大可以获得可靠数据的参数范围，并在温度-化学势平面上绘制相图。特别是达到低温是研究超致密物质行为等问题的一项重要任务，此外，我们现在要解决的问题是我们在项目的第一部分中无法解决的问题，即真实的时间中的动力学过程。在这里，分析的目的也将是参数区域的扩展和应用到新的，现实的模型。引用参考文献包括在应用程序中。

项目成果

The QCD phase diagram in the limit of heavy quarks using complex Langevin dynamics

• DOI: 10.1007/jhep09(2016)087
• 发表时间: 2016-06
• 期刊: Journal of High Energy Physics
• 影响因子: 5.4
• 作者: G. Aarts;Felipe Attanasio;B. Jäger;D. Sexty

Reweighting Lefschetz Thimbles

• DOI: 10.21468/scipostphys.5.5.044
• 发表时间: 2018-03
• 期刊: Proceedings of The 36th Annual International Symposium on Lattice Field Theory — PoS(LATTICE2018)
• 作者: Stefan Blücher;J. Pawlowski;M. Scherzer;Mike Schlosser;I. Stamatescu;Sebastian Syrkowski;Felix Ziegler

Status of Complex Langevin

• DOI: 10.1051/epjconf/201817501019
• 发表时间: 2017-08
• 作者: E. Seiler

Controlling complex Langevin simulations of lattice models by boundary term analysis

• DOI: 10.1103/physrevd.101.014501
• 发表时间: 2019-10
• 期刊: Physical Review D
• 影响因子: 5
• 作者: M. Scherzer;E. Seiler;D. Sexty;I. Stamatescu

Schwinger–Dyson equations and line integrals

SchwingerâDyson 方程和线积分

• DOI: 10.1088/1751-8121/aaefca
• 发表时间: 2019
• 期刊: Journal of Physics A: Mathematical and Theoretical
• 作者: L. L. Salcedo;E. Seiler
• 通讯作者: E. Seiler