Download - CGC, Full 3D Hydro, and Hadronic Cascade
CGC, Full 3D Hydro, CGC, Full 3D Hydro, and Hadronic and Hadronic
CascadeCascade
Tetsufumi HiranoTetsufumi Hirano
Department of Physics, University of TokyoDepartment of Physics, University of TokyoTH, U.Heinz, D.Kharzeev, R.Lacey, and Y.Nara, TH, U.Heinz, D.Kharzeev, R.Lacey, and Y.Nara, Phys.Lett.B636(2006)299,Phys.Lett.B636(2006)299,See also, TH and M.Gyulassy, Nucl.Phys.A769(2006)71.See also, TH and M.Gyulassy, Nucl.Phys.A769(2006)71.
The 19The 19thth International Conference on International Conference on Ultra-Relativistic Nucleus-Nucleus CollisionsUltra-Relativistic Nucleus-Nucleus Collisions
OutlineOutline
• Introduction: Three stages of bulk dynamics• Two possible hydro initial conditions
– (Conventional) Glauber-type (as a reference)– Color Glass Condensate
• Highlights from Glauber-type initial conditions• Elliptic flow from CGC initial conditions• Comparison of eccentricity • v2 in Cu+Cu collisions• Prediction at the LHC energy• Summary and outlook
Three Stages of Bulk DynamicsThree Stages of Bulk DynamicsFinal stage:• Hadronic transportHadronic cascade model, JAM
Initial stage:• Perfect fluidity of the QGPIdeal 3D hydro
Before Collisions:• Nuclear wave function Color Glass Condensate
0z
t
Detailed description of the CGC, QGP, and hadrons in a unified wayImportance for quantitative analyses of hard probe, J/etc.
•Thermalization…
Initial Conditions in Hydro
•Unintegrated gluon distributiona.la. Kharzeev, Levin, and Nardi•Gluon production via kT factorization formula •Count deposited energy in dV at (0,x,y,s), 0 = 0.6fm/c
[Reference Initial Condition]Transverse profile: Entropy density
Longitudinal Profile:Brodsky-Gunion-Kuhn triangle
Color Glass CondensateGlauber-BGK type
sx(fm) s
x(fm)
ene.
dens
ity
ene.
dens
ity
Two Hydro Initial Conditions Which Two Hydro Initial Conditions Which Clear the “First Hurdle” Clear the “First Hurdle”
1. CGC model Matching I.C. via e(x,y,) 2.Glauber model (as a reference) Npart:Ncoll = 85%:15%
Centrality dependence Rapidity dependence
Kharzeev,Levin, and NardiImplemented in hydro by TH and Nara
Highlights from Highlights from GlauberGlauber + QGP Fluid + QGP Fluid + Hadron Gas Model + Hadron Gas Model
TH et al.(’06); in preparation.
Good agreement for bulk (pT<~1.5GeV/c) What happens to the CGC case?
20-30%
vv22(N(Npartpart) from ) from CGCCGC + QGP Fluid + QGP Fluid
+ Hadronic Gas Model+ Hadronic Gas Model
Glauber: Early thermalization Discovery of Perfect Fluid QGPCGC: No perfect fluid? Additional viscosity
required in QGP
Important to understand initial conditions much better for making a conclusion
TH et al.(’06)
Adil, Gyulassy, Hirano(’06)
Large Eccentricity from CGC Initial Large Eccentricity from CGC Initial ConditionCondition
xx
yy
Pocket formula (ideal hydro): v2 ~ 0.2 @ RHICOllitrault(’92)
Hirano and Nara(’04), Hirano et al.(’06)Kuhlman et al.(’06), Drescher et al.(’06)
System Size Dependence of v2
(Eccentricity as an input)
(Ell
ipti
c fl
ow a
s an
out
put)
Response of the system depends on its size. Inconsistent with PHOBOS data ?
PHOBOS, nucl-ex/0610037
vv22(() @ LHC and v) @ LHC and v22(sqrt(s(sqrt(sNNNN))))
•Total v2 generated mainlyin the QGP phase
•v2 monotonically increases in the hybrid model. •Hadronic dissipation washes out a bump seen at low energies.
Teaney et al.(’02)
Summary and OutlookSummary and Outlook• Dynamical modeling of bulk matter
– Entropy production from CGC collisions– Evolution of perfect fluid QGP– Evolution of dissipative hadronic gas
• Importance of bulk for other observables.• v2 overshot due to large eccentricity in CGC
– Need viscosity in the QGP?
• Much more studies needed for initial states– Universal scaling from CGC? Fluctuation?
– Pre-thermalization stage? Instability? Isotropization?
Lappi and Venugopalan(’06)Drescher and Nara(’06)
Muronga, Rischke,Teaney, Heinz, Chaudhuri,Song, Baier, Romatschke, Wiedemann…
Mrowczynski, Arnold, Moore, Yaffe, Dumitru, Nara,Rebhan, Romatschke, Strikland, Venugopalan,…
Eccentricity from Universal Saturation Scale
Almost no difference btw. conventional and universal definition for Qs^2•Conventional saturation scale
•Universal saturation scalenear the origin
dN/ddN/d and v and v22 in Cu+Cu Collisions in Cu+Cu CollisionsPseudorapidity distribution v2() for charged hadrons
v2(pT) and v2(eta) from CGC initial conditions
vv22(model) > v(model) > v22(data)(data)
20-30%
Sensitivity of Different Assumptions Sensitivity of Different Assumptions in Early/Late Stagesin Early/Late Stages
??Gradual
freezeout(Hadronic rescattering)
?Discovery of
“Perfect Liquid”Sudden
freezeout
Color Glass Condensate
Glauber-typeInitialInitialConditionCondition
FreezeoutFreezeout
Sensitivity of Different Assumptions Sensitivity of Different Assumptions in Early/Late Stages in Early/Late Stages
?Discovery of Perfect fluid QGP & hadronic
corona
Gradual
freezeoutHadronic rescattering
?Discovery of
“Perfect Liquid”Sudden
freezeout
Color Glass Condensate
Glauber-typeInitialInitialConditionCondition
FreezeoutFreezeout
Consistency?Consistency?Elliptic flow Particle ratio
Issue: Conventional ideal hydro could not reproduce particle ratio.Solution: Introduction of chemical freezeout in hydro.
Interpretation: Accidental reproduction by ideal hydro. Necessity of dissipation in the hadron phase.
TH and M.Gyulassy(’06)
N.Arbex et al.(’01), TH and K.Tsuda(’02), D.Teaney(’02)
Hyd
ro:
P.H
uovi
nen
Dat
a: P
HE
NIX
PH
EN
IX w
hite paper
Consistency again!Consistency again!Elliptic flow Color Glass Condensate
Issue: CGC initial conditions were not implemented in hydro.Solution: Introduction of CGC initial conditions in hydro.
Interpretation: Larger eccentricity from CGC Necessity of dissipation even in the QGP phase!
TH and Y.Nara(’04)
Hyd
ro:
P.H
uovi
nen
Dat
a: P
HE
NIX
Results: K
harzeev and Levin(’01)D
ata: PH
OB
OS
Hirano,Heinz,Kharzeev,Lacey,Nara, PLB636(’06)299.
How Do Partons Get Longitudinal Momentum in Comoving System?Free Streaming eta=yFree Streaming eta=y
dN/dydN/dy
y
dN/dydN/dy
y
Sum of delta functionSum of delta function Width Width “Thermal” fluctuation“Thermal” fluctuation
Sheet:Sheet:eta=consteta=const