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Hot and dense QCD matter
APCTP-WCU Focus Program “From dense matter to campact stars in QCD and hQCD”, Pohang, May 24-June 4, 2010
Mei Huang IHEP, CAS
TPCSF, CAS
2
Content
I. QCD Phase structure chiral restoration & deconfinement phase transition
II. Locate CEP from viscosities shear viscosity/entropy density ratio
bulk viscosity/entropy density ratio
3
I. QCD Phase Structure
4
1974 ---- 1999 1999 ---- 2002
HM
QGP
CSCHM
QGP
5
Compact Star
sQGP E. Shuryak, I. Zahed
Pseudogap phase Hatsuda,Kunihiro
After 2003 High T part
6
After 2003 High density part
Abuki-Baym-Hatsuda-Yamamoto, arXiv:1003.0408
Darmstadt and Frankfurt CSC group, Phys.Rev.D72:034004,2005
Many people contributed on the rich structure of CSC
APCTP focus program 2006
7
After 2007: Chiral symmetric but confined phase
Quarkyonic and half-Skymion phase
L. McLerran, R. Pisarski
Phase diagram at large Nc Skymion crystal
See M. Rho’s talk
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HM
QGP
CSC
Can Quarkyonic phase be realized in real QCD phase diagram?
Fukushima, Hatsuda,arXiv:1005.4814
HM
QGP
CSC
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Quarkyonic phase in PNJL model
Different choices of Polyakov potential: fixed by lattice QCD at finite T
10Kenji Fukushima, arXiv:0803.3318
11
Quarkyonic phase in PLSM model
H. Mao, J. Jin, MH, arXiv:0906.1324
12
In PNJL or PLSM model, at zero baryon density, whether chiral phase transition and deconfinement phase transition coincide or not depends much on parameters used.
In these models, there are no interplay between chiral phase transition and deconfinement phase transition.
13
Lattice results on Tc at zero mu
Chiral limit: coincide
Physical quark mass (2+1):
RBC-Bielefeld: coincide
Wuppertal-Budapest: (crossover feature)
14
An equivalent order parameter for deconfinement phase transition:
Gattringer,PRL97(2006)032003Bilgici et.al. PRD77(2008)094007Braun, Hass,Marhauser,Pawlowski, arXiv:0908.0008
Order parameter of center symmetry
Confinement: center symmetry
Deconfinement:
center symmetry breaking
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The periodicity property of the quark fields change under the the gauge transformation Uz:
Dual observables:
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n=1: dressed Polyakov loop
Dual quark condensate:
order parameter of center symmetry
Dressed Polyakov loop in NJL model
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Chiral limit: coincide
T.Mukherjee, H.Chen,M.Huang, arXiv:1005.2482
18T.Mukherjee, H.Chen,M.Huang, arXiv:1005.2482
Physical quark mass:
crossover region
1st order:
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Why for 1st and 2nd phase transition?
T.Mukherjee, H.Chen,M.Huang, arXiv:1005.2482
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Why for crossover?
T.Mukherjee, H.Chen,M.Huang, arXiv:1005.2482
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Mass effect
Nf=2+1 in NJL model is in progress
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II. Locate CEP by viscosities
shear viscosity/bulk viscosity
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Relativistic Heavy Ion Collision
Discovery of “Perfect fluid” at RHIC
Hydrodynamics
???
24
A little bit Hydrodynamics
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Increase shear viscosity reduces elliptic flow!
P. Romatschke, U. Romatschke, nucl-th/0706.1522
Before 2003, people believed that de-confined QCD matter would be weakly coupled gas. Therefore, bulk viscosity is neglected, only consider shear viscosity corrections to the ideal hydro.
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Discovery of sQGP at RHIC
Low shear viscosity
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Handling strongly coupled system by using AdS/CFT
Minimum bound?
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sQGP: Most “perfect fluid” known
• Lattice: C0.13 0.03, at T=1.65 Ts
Nakamura-Sakai(2004)
Meyer (2007)
~ 10s
• Water
10.08
4s
Policastro, Son, and Starinets;Kovton, Son and Starinets; Buchel, J. Liu; Nakamura, Sin; Maeda, Natsuume, Okamura; ……
• N=4 SYM:
0.1 0.2s
• RHIC: Teaney (2003)
Romatschke-Romatschke (2007)
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Interesting global feature of /s
Does /s make some sense?
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Phys.Rev.Lett.97:152303,2006
Proposal:
Sufficient precise Experimental measurement of /s to pinpoint the location of phase transitions or crossover.
Empirical observation:
31
Lacey et al., PRL 98:092301,2007
Probe CEP by /s
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Results from real scalar model
Yagi, Hatsuda, Miake, “Quark-Gluon Plasma”
Can /s characterize phase transitions?
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1, Minimum at Tc, most difficult condition for momentum transportation.
2. The value of /s at phase transition decreases with increases of coupling strength
J.W Chen, MH, Y.H. Li, E. Nakano, D.L.Yang, Phys.Lett.B670:18-21,2008, arXiv: 0709.3434
/s characterizes phase transitions CJT+Boltzmann Eq
Dmitri Kharzeev, Kirill Tuchin arXiv:0705.4280 [hep-ph],F.Karsch, Dmitri Kharzeev, Kirill Tuchin arXiv:0711.0914 [hep-ph],Harvey Meyer arXiv:0710.3717 [hep-ph],
However: large bulk viscosity of QCD matter near phase transition
Pure gluodynamics 2-flavor case
Bulk viscosity is related to nonconformality
Several quantities measure conformality
LQCD results:
trace anomaly shows a sharp peak near phase transition
BNL-Columbia-RBRC-Bielefeld, arXiv:0710.0354 Bielefeld, hep-lat/9602007
BNL-Columbia-RBRC-Bielefeld arXiv:0710.0354
LQCD results:
soft EOS & small sound velocity near phase transition
Gubser et al, 0804.1950
AdS/CFT
Gravity duals, nonconformal
Bulk viscosity in gravity dual models
Results from scalar model: 2nd order phase transition
Trace anomaly: height is DOF dependent
Baochun Li, Mei Huang, Phys.Rev.D78:117503,2008 arXiv: 0807.0292
EOS & sound velocity
Baochun Li, Mei Huang, Phys.Rev.D78:117503,2008 arXiv: 0807.0292
Bulk viscosity/entropy density
Baochun Li, Mei Huang, Phys.Rev.D78:117503,2008 arXiv: 0807.0292
42
Results from a more realistic model: PLSM model
H. Mao, J. Jin, M. Huang, arXiv: 0906.1324[hep-ph]
Comparing with LQCD
43
Sound velocity square at Tc: 0.05 in PLSM, 0.07 in LQCD
H. Mao, J. Jin, M. Huang, arXiv: 0906.1324[hep-ph]
44
Comparing with LQCD: Bulk viscosity/entropy density
H. Mao, J. Jin, M. Huang, arXiv: 0906.1324[hep-ph]
45
Dependence of bulk viscosity/entropy density on the order of phase transition: large for 1st order phase transition, small for crossover. Thus, bulk viscosity/entropy density is better than shear viscosity/entropy density to probe CEP.
H. Mao, J. Jin, M. Huang, arXiv: 0906.1324[hep-ph]
46
Shear viscosity: how much entropy is produced bytransformation of shape at constant volume
Bulk viscosity: how much entropy is produced bytransformation of volume at constant shape
Physical quantities related bulk viscosity
Generated bytranslations
Generated bydilatations
47
Conclusion and discussion
1, Interplay between chiral phase transition and
deconfinement phase transition.
2, Locate CEP by bulk viscosity/entropy density
Observables related to bulk viscosity?
Radial flow?
48
What’s the effect of large bulk viscosity near Tc?
Breakdown of hydrodynamic picture
Slow down the expansion of the system
Clustering at hadroniztion
……
G.Torrieri, B.Tomasik, I.Mishustin, arXiv:0707.4405[hep-ph]
G.Torrieri, I.Mishustin, arXiv:0805.0422[hep-ph]
R.J.Fries, B.Muller,A.Schafer, arXiv:0807.4333[hep-ph]