A New State of Matter: Quark-Gluon Plasma Pengfei Zhuang (Tsinghua University) * Quark-Gluon Plasma * Experiment Results * Theory * Outlook

熟悉物态: 固态,液态,气态,电磁等离子体 问题: 是否存在由夸克和胶子组成的物态？ 物质科学包含物质的结构和状态 结构： 问题: 看不见的夸克,质量起源,真空结构 状态： 熟悉物态: 固态,液态,气态,电磁等离子体 问题: 是否存在由夸克和胶子组成的物态？ 2004 诺贝尔物理奖 David J. Gross H. David Politzer Frank Wilczek

T.D.Lee： In order to study the question of ‘vacuum’, we must turn to a different direction: we should investigate some ‘bulk’ phenomena by distributing high energy over a relatively large volume.” --------------- Rev. Mod. Phys. 47, 267(1975) from 1897 to present: to comprehend the largest, we need only understand the smallest. from present to 21st century: to know the smallest, we need also the largest!

QCD Phase Diagram 温度密度效应 —>波函数重叠 —> 最深层次物质形态 夸克胶子等离子体，QGP Temperature Neutron stars Early universe (LHC, RHIC) nuclei nucleon gas hadron gas colour superconductor quark-gluon plasma Tc r0 critical point ? QCD Phase Diagram

superconductivity superfluidity 夸克物质：高度交叉的领域， 粒子物理,核物理,凝聚态物理,宇宙学,天体物理,…… related to early universe related to compact stars related to relativistic heavy ion collisions

CSR/兰州(即将运行): Elab = 1 A GeV FAIR/GSI(巳批准): 40 A GeV NICA/JINR (巳批准): 相对论重离子碰撞实验 CSR/兰州(即将运行): Elab = 1 A GeV FAIR/GSI(巳批准): 40 A GeV NICA/JINR (巳批准): SPS/CERN(巳关闭): 160 A GeV RHIC/LBL(正在运行): LHC/CERN(即将运行): 制造高重子数密度条件 制造高温条件

Heavy ion Exp. @ BNL/RHIC Au－Au@200A GeV Experiments STAR

Heavy ion Exp.@ CERN/LHC (27km) Pb-Pb@5.5A TeV Heavy ion Exp.@CERN/SPS (6.7km) Pb-Pb@17.3GeV

Heavy ion Exp.@ GSI/SIS200 U+U@Elab = 40A GeV

兰州CSR（Cooling Storing Ring）大科学工程

QGP产生的标志——信号 喷注淬火(Jet quenching): 高能喷注在热密物质中运动会损失能量 集体流(Collective flow): 不是静态系统，体系的膨胀会产生集体流 J/ψ粒子产额压低: 重夸克系统在热密物质中由于Debye屏蔽 而解体 电磁信号 电磁信号是最干净的信号 奇异粒子增加 Quark Gluon Plasma中奇异夸克成对产生 …… QGP产生的标志——信号

What RHIC has told us … STAR: NPA757, 102 (05) Jet quenching, Large v2, NCQ-scalings, Large radial flow STAR models As we know, until now, RHIC has accumulated huge amount of data. Among these data, I think the first key observation is ‘jet quenching’, i.e. in central Au-Au collisions, the yield of high pt particle per binary collision is suppressed compared to that of pp collisions at the same energy. This results indicate very high gluon density at the early stage. The second one is the large elliptic flow value in semi-central Au-Au collisions. As we also see in the plot, hadronic transport models can not reproduce the data, which means partonic phase is essential to generate such high pressure at early stage. The third one is the number of constituent quark scaling of elliptic flow at intermediate pt region. According to the coalescence model, the scaled v2 will be the v2 of partons at hadronization. This phenomenon is another indication of deconfinement at RHIC. The fourth one is the large radial flow. This figure shows the results of the blast wave model fitting to pi,k,p spectra for differenct centralities. As we can see, with the increase of centrality, the collective velocity becomes larger and larger, for the most central collisions, it even reaches .6 speed of light. All these data shown here strongly indicate that a fast expanding partonic matter has been created at RHIC. The question now is whether thermalization is reached.

热平衡理论: 有限温度量子场论(场论+统计) 夸克物质理论 热平衡理论: 有限温度量子场论(场论+统计) 定域平衡体系的时空演化: 相对论流体力学 状态方程 非平衡体系的时空演化:

LHC RHIC Tc FAIR CSR QCD 相图： (1.5-2) Tc BCS BEC pair dissociation line BCS Tc (1.5-2) Tc BEC sQGP QCD 相图： LHC RHIC FAIR CSR 新现象: 强耦合夸克胶子等离子体 (sQGP) 高密度时的色超导，π超流，等 主要问题: 1)sQGP的性质 RHIC, LHC/ALICE 2)sQGP在 RHIC 和 LHC产生的信号 RHIC,LHC/ALICE 3)临界相变点 (tricritical) 的位置 FAIR,NICA 4)手征对称性部分恢复 CSR 主攻方向: 强耦合夸克物质理论及其信号

QCD is non-perturbative even at extremely high temperature ! the validity of a weak coupling expansion depends not only on the strength of the coupling, but also on the number of active degrees of freedom ! coupling α solid dynamics liquid gas ideal gas non-perturbative perturbative only here ! density n collectivity

Strongly Coupled Quark Matter ● lattice 2009: more non-perturbative when charm quark is thermalized, 50% contribution ! conclusion: non-perturbative QCD even at extremely high T ! ● two possible states of sQGP: a) independent quasi-partons b) partons + bound states

QCD at High Density T ● nB atom gas QCD ● lattice 2009: searching for the QCD critical point in canonical ensemble T ● nB ● does the quarkyonic matter exist in real world with Nc=3 and what is the measurable consequence of the quarkyonic matter ? atom gas ● D.Son: no deconfinement in isospin matter due to pion superfluidity, even at extremely high isospin density QCD ● BCS-BEC crossover in QCD phase transitions at high density ● Fridel oscillation at high density

AdS/CFT Correspondence weak coupling in gravity theory corresponds to strong coupling in gauge theory Kovtun, Son, Starinets, PRL94, (2005)111601: for any physical system Kapusta, QM06, Shanghai: theory calculation Prakash et al., Phys. Rep. 227, (1993)321. constructed with data Hatsuda, QM06, Shanghai minimal at the critical point, a possible way to pinpoint the location of a QCD phase transition Problems: CFT is not QCD, the coupling constant does not run,…… pQCD lattice AdS/CFT Blaizot, Mclerran, QM06, Shanghai

QGP Study in China 实验：参加STAR/RHIC国际合作组 科大，清华 (MRPC，重要贡献） 华中师大，上海应用物理所，山大，哈尔滨工大，…… 理论： QCD相变理论 高能所,科大,北大,南大,清华,等 相对论重离子碰撞理论 华中师大,山大,清华,等 王恩科,等给出有限温度和密度下具有细致平衡效应的喷注能量损失 王群,等：BCS-BEC

Gapless Color Superconductivity 通过考虑色电中性条件对色超导态的影响，发现激发的准粒子能量可以为零，引导了无能隙色超导态的提出。在我们2003年提出这一新概念后，迅速成为QCD相变研究的一个热点。

Pion Superfluidity 解析证明了π超流的临界化学势等于真空中的π质量，纠正了以往文献中认为两者只是近似相等的结论，引导了高密π超流的研究。

J/ψ Puzzle

Partonic Wind

Outlook 实验 SPS: 达到了产生QGP的条件 RHIC: 发现了产生QGP的一些信号 LHC: Properties of QGP FAIR,NICA,RHIC energy scan: QCD critical point CSR: Chiral symmetry restoration 理论 非微扰强相互作用多体问题难度很大 QCD at high density Strongly coupled quark matter Sensitive QGP signatures RHIC AdS/CFT Compact Stars Early Universe QGP 谢谢 ！ BCS-BEC Lattice