规范引力对偶在QCD相图中的应用

We focus on applications of the AdS/CFT in QCD phenomenon in this project. Generally speaking, there are two approaches to investigate this topic, the one is "top-down", the other is "bottom-up". We construct hCD model to describe the Regge behavior of hardron and chiral symmetry breaking and restoration. In order to confirm the hQCD model in zero temperature captures the most important characterizes, we will study instability of rho meson induced by strong magnetic field.We are working on the QCD phase diagram from holographic perspective specially in the hQCD model with including chemical potential and temperature. There are still many open problems in QCD phase diagram. Recently, lattice calculation shows that there are two kinds of phase transition near the critical end point of deconfinement transition in heavy quark limit. The one is first order phase transition in small chemical potential region and the other is continuous phase transition in large chemical potential region. This picture is a little bit different from the conventional studies from effective field theories. How to realize the deconfinement phase transition in hQCD is one of most important issues. Furthermore, there have been no complete model to study both deconfinement phase transition and chiral phase transition. There are two approaches to study the chiral phase transition normally, the one is to investigate the chiral condensation and the other is to study the difference between the vector meson and axial vector meson. We will choose the first way to understand the phase diagram. Finally, we would like complete the hQCD phase diagram with considering the color flavor locked phase which is predicted by effective field theory. The picture is simple when chemical potential goes to much higher. The dominant interaction between quark and quark with same electric charges will be strong interaction and quark pairs will appear. The situation is similar to the generation of Cooper pairs in normal superconductor physics. Motivated from understanding the complete phase diagram, we would like construct holographic model in Einstein+Dilaton+Maxwell (EDM) system to contain the three aspects of QCD phase diagram systematically. Based on these studies, we expect to understand the relation between gravity and QCD well from gauge/gravity perspective. We also expect to give some lesons to build up the relation between string theory and QCD phenomenons.

在AdS/QCD 中,主要有两种方法来研究QCD 现象学, 其中一种方法是"top-down",另外一种方法是"bottom-up"。该项目主要用势重构方法从零温QCD现象学构建全息QCD(hQCD)模型。我们从零温QCD现象学中的强子能谱，核子形状因子，QCD跑动耦合常数来限制全息QCD模型的度规形式以及模型中的参数。基于零温全息QCD(hQCD)模型，我们推广到有限温度有限密度的全息QCD(hQCD)。根据该模型，我们主要讨论QCD相图中的手征相变，解禁闭相变，色味解禁闭相变过程。为了更进一步研究hQCD相图中的具体性质，我们将计算QGP相中的体粘滞系数和剪切粘滞系数，以及夸克在QGP中运动的拖拽力。通过这些计算，我们希望跟格点QCD计算的结果和有效场论计算的结果比较，更进一步的完善hQCD模型。在这些模型研究的基础上，我们希望势重构方法能为连接弦理论和低能QCD现象学提供借鉴和指导。

该项目主要从两个角度来研究QCD现象学中的相变问题。第一个方面主要从"bottom-up" 方法出发。利用势重构方法构建面向真实QCD相图的全息QCD(hQCD)模型。为了更进一步研究hQCD 相图中的具体性质，我们将计算QGP 相中的体粘滞系数和剪切粘滞系数，以及QGP中的jet queching系数 。通过这些计算，我们希望跟格点QCD 计算的结果和有效场论计算的结果比较，更进一步的完善hQCD 模型。在这些模型研究的基础上，细化了构造全息QCD模型并定量的统一地描述热QCD的手征相变和退禁闭相变过程中味道对称性破缺效应。。第二个方面主要是领用纠缠熵来刻画相变的性质。在相变过程中，一直系统的自由度会发生突然的变化。纠缠熵能很好的描述这些自由度的变化。首先，我们在简单场论系统中来研究纠缠熵的普适的性质。进而，这些性质会指导我们来研究复杂系统，比如QCD系统的相变过程。到目前为此，本项目已取得一些比较好的研究成果并达到预期目标，现有13篇相关研究论文，其中9篇文章已在国际重要物理核心SCI期刊上发表，4篇文章在投稿中。此外，还有2篇文章正在撰写阶段。