论文标题
晶格QCD的光谱和运输特性
Spectral and transport properties from lattice QCD
论文作者
论文摘要
在这些讲义中,我们将讨论从Lattice QCD提取光谱和运输特性方面的最新进展。我们将重点关注热QCD培养基的探针的结果以及传输系数,这些系数是描述产生培养基的演变的流体动力和传输模型的重要成分。这些包括电磁探针,例如发射光子和障碍的速率,夸克光谱函数以及传输系数,例如夸克gluon等离子体(QGP)的电导率或重型风味扩散系数。所有这些实时数量均在矢量介子光谱函数中编码。在欧几里得晶格QCD计算中,无法直接确定光谱函数,但可以在分析中从虚构到实时进行分析。因此,可以将光谱函数与相应的欧几里得相关函数联系起来。在以下各节中,我们将讨论确定所需相关函数的过程,并从晶格QCD相关器中提取光谱函数。我们将说明从连续性外推相关函数中获得光谱函数和相关物理可观察物的概念和方法。我们将重点关注从连续外推晶格相关函数获得的结果,该功能需要大而细的晶格,到目前为止,只有在淬灭近似中才有可能。我们将仅对晶格QCD进行简要介绍,并参考教科书[1,2,3,4]和讲义注释[5],以获取对晶格场理论的更详细介绍。对于本讲座中介绍的主题,我们还希望在极端条件下提到有关QCD热力学和QCD相变[5,6,7]和Quarkonium的概述文章[8]。
In these lecture notes we will discuss recent progress in extracting spectral and transport properties from lattice QCD. We will focus on results of probes of the thermal QCD medium as well as transport coefficients which are important ingredients for hydrodynamic and transport models that describe the evolution of the produced medium. These include electromagnetic probes, like the rates of emitted photons and dileptons, quarkonium spectral functions as well as transport coefficients like the electrical conductivity or heavy flavor diffusion coefficients of the quark gluon plasma (QGP). All these real time quantities are encoded in the vector meson spectral function. A direct determination of the spectral functions is not possible in Euclidean lattice QCD calculations but they can be analytically continued from imaginary to real time. Therefore it is possible to relate the spectral function to the corresponding Euclidean correlation functions. In the following sections we will discuss the procedure to determine the required correlation functions and the extraction of the spectral functions from lattice QCD correlators. We will illustrate the concepts and methods to obtain spectral functions and related physical observables from continuum extrapolated correlation functions. We will focus here on results obtained from continuum extrapolated lattice correlation functions, which requires large and fine lattices, which so far was only possible in quenched approximation. We will only give a brief introduction to lattice QCD and refer to the textbooks [1,2,3,4] and lecture notes [5] for more detailed introductions to lattice field theory. For the topics addressed in this lecture note we also like to refer to the overview articles on QCD thermodynamics and the QCD phase transition [5,6,7] and quarkonium in extreme conditions [8].