1. Huichao Song The Ohio State University Lawrence Berkeley National Lab Viscous Hydro +URQMD In collaboration with S.Bass, U.Heinz, C.Shen, P.Huovinen & T.Hirano (?) 06/14/2004 May24- July 16, INT Seattle, WA Quantifying the Properties of Hot QCD Matter Supported by DOE

2. Viscous hydrodynamics S.Bass Conservation laws: - Israel-Stewart eqns.

3. Viscous hydrodynamics S.Bass Conservation laws: - Israel-Stewart eqns. viscous hydro: near-equilibrium system pre-equilibrium dynamics + viscous hydro + hadron cascade Initial conditions viscous hydro + final conditions

4. Ideal/ViscousHydro + URQMD 2+1 Ideal/Viscous Hydro Hadron Cascade S.Bass MC- Particle Generator T sw Convertor: MC particle generator VIS -MC

5. extracting QGP viscosity from data Luzum & Romatschke, PRC 2008 GlauberCGC -Effects from highly viscous & non-chemical equilibrium hadronic stage, bulk viscosity … NOT so fast !

6. Effects of viscosity & chemical composition of HRG ~30% PCE vs.CE (HRG) Ideal hydro P. Huovinen 07 - Does hadronic viscosity and partially equilibrium chemistry balance each other in elliptic flow? Is it safe to neglect both of them, when extracting QGP viscosity? Ideal hydro vs ideal hydro +hadron cascade ~30%

7. Ideal / viscous hydro+URQMD SM-EOS Q (CE) vs. EOSL-PCE

8. ideal hydro vs. ideal hydro+URQMD (EOSL-PCE) - EOS L-PCE : Hadronic viscosity (URQMD) leads to ~20% viscous v 2 suppression EOS L-PCE

9. ideal hydro +URQMD: SM-EOSQ(CE) vs. EOSL-PCE - EOS L-PCE: Hadronic viscosity (URQMD) leads to ~20% viscous v 2 suppression - SM-EOS Q (CE): effects from hadronic viscosity and PCE (in URQMD) cancel each other in elliptic flow v 2 (Ideal hydro+URQMD) SM-EOS Q (CE)EOS L-PCE

10. SM-EOSQ(CE) : viscous vs. ideal hydro +URQMD - SM-EOS Q (CE): effects from hadronic viscosity and PCE (URQMD) cancel each other in elliptic flow v 2 (ideal hydro+URQMD) -This is no longer true in viscous hydro+URQMD -much larger v 2 suppression for P T >1GeV: effects from shear viscous correction / EOS SM-EOS Q (CE)

11. EOSL-PCE : ideal vs. viscous hydro + URQMD -EOS L-PCE: additional v 2 suppression by URQMD (ideal/viscous hydro + URQMD behave similarly) -Larger URQMD viscous v 2 suppression in ideal hydro +URQMD EOS L-PCE

12. Spectra: SM-EOS Q(CE) vs. EOSL-PCE -EOS L-PCE (correct chemistry below T ch ) is preferable EOS L-PCE SM-EOS Q (CE)

13. viscous v 2 suppression EOS L-PCE -EOS L-PCE: v 2 suppression increases from ~20% (min visc hydro) to ~30% (min visc hydro + URQMD)

14. viscous v 2 suppression EOS L-PCE -EOS L-PCE: v2 suppression increases from ~20% (min visc hydro) to ~30% (min visc hydro + URQMD) ---> significantly reduces the extracted QGP viscosity

15. ideal/viscous hydro +URQMD: mass splitting -Radial flow increases the mass splitting between pion and proton; similar behavior in ideal/ viscous hydro +URQMD EOS L-PCE

16. More Systematic study

17. Inte v 2 : hydro decouple at T sw vs. hydro+URQMD -v 2 is not fully developed at T sw ; -positive ecc. at T sw  additionally increase of v 2 in URQMD

18. Inte v 2 : ideal hydro, vis hydro, vis hydro+URQMD -Additional v 2 suppression in URQMD (hadronic stage is highly viscous)

19. viscous v 2 suppression: hydro vs. hydro+URQMD -larger URQMD viscous v 2 suppression for smaller systems -viscous hydro + URQMD: smaller URQMD viscous v 2 suppression, comparing with ideal hydro + URQMD

20. ideal vs viscous hydro & ideal vs viscous hydro +URQMD -Viscous v 2 suppressions are significantly reduced after a proper treatment of hadronic matter (URQMD)

21. : ideal Hydro + URQMD -Hadronic viscosity from URQMD increase the slope of

22. : ideal /Viscous Hydro + URQMD (I) -hadronic viscosity from URQMD increases the slope of

23. -hadronic viscosity from URQMD increase the slope of - v 2 is not fully saturated at T sw  the increase of the slope : ideal /Viscous Hydro + URQMD (II)

24. : experimental data Thanks for A. Tang for Exp data -Experimental data: v 2, dN/dy ; theoretical estimations: ecc. S (Glauber/CGC) -larger slope and magnitude for v 2 /ecc. for glauber initial profile GlauberCGC

25. A hint for min vis. liquid with CGC initialization Thanks for A. Tang for Exp data - v 2 /ecc from hydro +URQMD is not sensitive to Glauber /CGC or optical/ fluctuation initializations (need some further calculations) GlauberCGC -Theoretical curves are all from Glauber initialization (add cures in the future ) -Overlap area are different for CGC and Glauber initializations

26. viscous hydro+URQMD -- a try to extract the hadronic viscosity vs. viscous hydro with EOSL-PCE is an essential input for the calculations here

27. inte v2 from hydro +URQMD with diff. T sw -with a “perfect” and “correct” chemical components (PCE) for hadrons phase, final results from hydro +URQMD should not be sensitive to T sw - is not enough for hadronic viscosity

28. inte v2 from hydro +URQMD with diff. T sw - is not enough for hadronic viscosity - over suppresses v2 for T=165-150 MeV, but not enough for T<130 MeV

29. inte v2 from hydro +URQMD with diff. T sw - is not enough for hadronic viscosity - over suppresses v 2 for T=165-150 MeV, but not enough for T<130 MeV

30. extract from URQMD (a first try) a hint? - is not enough for hadronic viscosity - over suppresses v2 for T=165-150 MeV, but not enough for T<130 MeV

31. inte v2 from hydro +URQMD with diff. &T sw

33. extract from URQMD (a first try) -please do NOT take the above number too seriously -need further detailed extraction - such extraction gives a special trajectory of URQMD dynamic

34. A Short Summary -when extracting the QGP viscosity, one need to consider the effects of hadronic viscosity and the hadronic chemical components -with viscous hydro+URQMD become available, these two above uncertainties are naturally eliminated -with a EOS correctly describe PCE HG, it is “somewhat” safe to swtich hydro to URQMD at lower temperature ---> extract the effective URQMD viscosity at some specific dynamical trajectory by comparing hydro with and hydro+URQMD

35. Thank You