1 hirano

CGC, Full 3D Hydro, and Hadronic Cascade: 

CGC, Full 3D Hydro, and Hadronic Cascade Tetsufumi Hirano Department of Physics, University of Tokyo TH, U.Heinz, D.Kharzeev, R.Lacey, and Y.Nara, Phys.Lett.B636(2006)299, See also, TH and M.Gyulassy, Nucl.Phys.A769(2006)71. The 19th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions

Outline: 

Outline 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 Dynamics: 

Three Stages of Bulk Dynamics Final stage: Hadronic transport Hadronic cascade model, JAM Initial stage: Perfect fluidity of the QGP Ideal 3D hydro Before Collisions: Nuclear wave function  Color Glass Condensate 0 z t Detailed description of the CGC, QGP, and hadrons in a unified way Importance for quantitative analyses of hard probe, J/Y, etc. Thermalization…

Initial Conditions in Hydro: 

Initial Conditions in Hydro Unintegrated gluon distribution a.la. Kharzeev, Levin, and Nardi Gluon production via kT factorization formula Count deposited energy in dV at (t0,x,y,hs), t0 = 0.6fm/c [Reference Initial Condition] Transverse profile: Entropy density Longitudinal Profile: Brodsky-Gunion-Kuhn triangle Color Glass Condensate Glauber-BGK type hs x(fm) hs x(fm) ene.density ene.density

Two Hydro Initial Conditions Which Clear the “First Hurdle” : 

Two Hydro Initial Conditions Which Clear the “First Hurdle” 1. CGC model Matching I.C. via e(x,y,h) 2.Glauber model (as a reference) Npart:Ncoll = 85%:15% Centrality dependence Rapidity dependence Kharzeev,Levin, and Nardi Implemented in hydro by TH and Nara

Highlights from Glauber + QGP Fluid + Hadron Gas Model: 

Highlights from Glauber + QGP Fluid + 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%

v2(Npart) from CGC + QGP Fluid + Hadronic Gas Model: 

v2(Npart) from CGC + QGP Fluid + Hadronic Gas Model Glauber: Early thermalization Discovery of Perfect Fluid QGP CGC: 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 Condition: 

Large Eccentricity from CGC Initial Condition x y Pocket formula (ideal hydro): v2 ~ 0.2e @ RHIC Ollitrault(’92) Hirano and Nara(’04), Hirano et al.(’06) Kuhlman et al.(’06), Drescher et al.(’06)

System Size Dependence of v2: 

System Size Dependence of v2 (Eccentricity as an input) (Elliptic flow as an output) Response of the system depends on its size.  Inconsistent with PHOBOS data ? PHOBOS, nucl-ex/0610037

v2(h) @ LHC and v2(sqrt(sNN)): 

v2(h) @ LHC and v2(sqrt(sNN)) Total v2 generated mainly in 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 Outlook: 

Summary 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: 

Eccentricity from Universal Saturation Scale Almost no difference btw. conventional and universal definition for Qs^2 Conventional saturation scale Universal saturation scale near the origin 

dN/dh and v2 in Cu+Cu Collisions: 

dN/dh and v2 in Cu+Cu Collisions Pseudorapidity distribution v2(h) for charged hadrons

v2(pT) and v2(eta) from CGC initial conditions: 

v2(pT) and v2(eta) from CGC initial conditions v2(model) > v2(data) 20-30%

Sensitivity of Different Assumptions in Early/Late Stages: 

Sensitivity of Different Assumptions in Early/Late Stages ? ? Gradual freezeout (Hadronic rescattering) ? Discovery of “Perfect Liquid” Sudden freezeout Color Glass Condensate Glauber-type Initial Condition Freezeout

Sensitivity of Different Assumptions in Early/Late Stages: 

Sensitivity of Different Assumptions in Early/Late Stages ? Discovery of Perfect fluid QGP & hadronic corona Gradual freezeout Hadronic rescattering ? Discovery of “Perfect Liquid” Sudden freezeout Color Glass Condensate Glauber-type Initial Condition Freezeout

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) Hydro: P.Huovinen Data: PHENIX PHENIX white 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) Hydro: P.Huovinen Data: PHENIX Results: Kharzeev and Levin(’01) Data: PHOBOS Hirano,Heinz,Kharzeev,Lacey,Nara, PLB636(’06)299.

How Do Partons Get Longitudinal Momentum in Comoving System?: 

How Do Partons Get Longitudinal Momentum in Comoving System? Free Streaming eta=y dN/dy y dN/dy y Sum of delta function Width “Thermal” fluctuation Sheet: eta=const