Recent Progress in the Study on
Quark Matter and Its Realization in Heavy Ion Collisions
庄鹏飞 (清华大学)
高能物理大会，南昌2010
沉痛悼念和怀念刘连寿教授
QCD Phase Transitions and Relativistic Heavy Ion Collisions
FAIR U+U@Elab = 40A GeV
RHIC Au+Au@√s = 200A GeV
deconfinement,
chiral symmetry restoration,
color superconductivity,
pion superfluidity, ……
CSR U+U@Elab = 0.6A GeV
STAR合作组中国成员：
清华大学
中国科技大学
华中师范大学
山东大学
上海应用物理所
兰州近代物理所
LHC Pb+Pb@√s = 5.5A TeV
Strongly Coupled Quark Matter
pair dissociation line
sQGP
BEC
BCS
lattice 2009:
more non-perturbative when charm quark
is thermalized, 50% contribution !
Point:
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 !
CBS  3
BS  B S
S2  S
2
 3
BS
S2
Conclusion: two possible sQGP states:
a) independent quasi-partons
b) partons + bound states
● lattice 2009:
T
QCD at High Density
● BCS-BEC crossover in QCD
searching for the QCD critical
● point in canonical ensemble
nB
QCD
cold atoms
● does the
quarkyonic matter
exist in real world
with Nc=3 and what
is the measurable
consequence of the
quarkyonic matter ?
He and Zhuang, PRD2007,2008,2009
● D.Son:
no deconfinement in isospin matter
due to pion superfluidity, even at
extremely high isospin density
● Fridel oscillation at high density
王群,等 PRD2008
QCD at high temperature and density:
刘玉鑫,宗红石,陈继胜,彭光雄,…
AdS/CFT Correspondence
weak coupling in gravity theory corresponds to strong coupling in gauge theory
Kovtun, Son, Starinets, PRL94, (2005)111601:

Bulk viscosity
黄梅,等 PRD2008,2009
1

s 4
pQCD
lattice
AdS/CFT
Conclusion:
minimal  / s and maximum  / s
at the critical point, a possible way
to pinpoint the location of a QCD
phase transition
重夸克介子的熔解温度
侯德富,等 JHEP2008, 2009
Problems:
CFT is not QCD, the coupling constant in AdS/CFT does not run, …
6
Signals of QGP Produced in Heavy Ion Collisions
Jet quenching: (王恩科,…)
喷注在热密物质中损失能量
Collective flow: (马余刚,刘峰,…)
体系的膨胀会产生集体流
strong fluctuations: (吴元芳,…)
在QCD临界点附近
J/ψ Suppression: (唐泽波,许晓明,…)
热密物质中有Debye屏蔽
Electromagnetic Signals: (周代翠,…)
电磁信号是最干净的信号
Strangeness enhancement: (杨纯斌,陈列文,…)
QGP中奇异夸克成对产生
Local Parity Violation:
高温高密时对称性自发破缺
Signals from RHIC
Jet quenching
NCQ-scaling
STAR

Large v2

models
Large radial flow
Jet quenching
a matter at parton level at RHIC !
Local Parity Violation
Lee and Wick (PRD1973,1974):
spontaneous P and T violation at high temperature
Kharzeev (PRL1998, PLB2006):
P-odd bubbles in deconfined QCD vacuum with Θ-term


2 
a
g
F
F
a

32 2
  x , t   0 in the bubbles
possible realization in non-central heavy ion collisions:
3 Puzzles in Heavy Ion Collisions (QM2009)
1)DLS Puzzle
low-mass dilepton enhancement,
partial chiral restoration?
A challenge for CSR!
E=1 A GeV
3) J/Psi puzzle:
RAA (|y|<0.35) > RAA (1.2<|y|<2.2)
RAA (RHIC, |y|<0.35) ≈ RAA (SPS)
2)HBT Puzzle
fireballs at SPS and RHIC have
almost the same size !
J/Psi Production at RHIC and LHC
Liu, Yan, Xu, Zhuang, PRL2006, PLB2009
J/Ψ suppression in hot matter (Matsui and Satz, 1986)
Our approach:
J/Ψ transport equation with QCD gluon dissociation
+ relativistic hydrodynamic equations
+ QCD equation of state
12
Partonic Wind at RHIC and LHC
Zhu, Xu, Zhuang, PLB2007, PRL2008
DD angular correlation is a sensitive probe of sQGP:
NN collisions: back-to-back correlation
RHIC: almost no correlation
LHC: near-side correlation
c quark motion in QGP:
we take drag coefficient as
a parameter charactering
the coupling strength
QGP evolution:
ideal hydrodynamics
13
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 RHIC
Sensitive QGP signatures
谢谢 ！
Compact
Stars
BCS-BEC
AdS/CFT
QGP
Early
Universe
Lattice
14