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What can we learn from hydrodynamic analysis at RHIC?

Workshop on Quark-Gluon-Plasma Thermalization August 10-12, TU Wien, Vienna, Austria. What can we learn from hydrodynamic analysis at RHIC?. Tetsufumi Hirano Dept. of Physics, Columbia Univ. T.H. and M.Gyulassy, nucl-th/0506049 T.H., Y.Nara et al ., in preparation. Outline.

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What can we learn from hydrodynamic analysis at RHIC?

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  1. Workshop on Quark-Gluon-Plasma Thermalization August 10-12, TU Wien, Vienna, Austria What can we learn from hydrodynamic analysis at RHIC? Tetsufumi Hirano Dept. of Physics, Columbia Univ. T.H. and M.Gyulassy, nucl-th/0506049 T.H., Y.Nara et al., in preparation.

  2. Outline • Perfect fluidity of sQGP core and highly dissipative hadronic corona • CGC + full 3D hydro + cascade • Hydrodynamic analysis suggests even a signal of DECONFINEMENT?!

  3. Our claims: • Ideal hydrodynamics accidentally reproduces these data! • Nevertheless, “perfect fluidity of the sQGP” statement still holds. • WHY!!!??? Basis of the Announcement PHENIX white paper NA49(’03) Integrated elliptic flow Differentialelliptic flow Common initial time in hydro ~ 0.6-1.0 fm/c A big surprise!

  4. Classification of Hydro Models Model CE: Kolb, Huovinen Heinz, Hirano… Model PCE: Hirano, Teaney; Kolb… Model HC: Teaney, Shuryak, Bass, Dumitru, Nonaka… T ~1 fm/c QGP phase Perfect Fluid of QGP Tc ~3 fm/c Chemical Equilibrium EOS Partial Chemical Equilibrium EOS Tch Hadronic Cascade Hadron phase Tth Tth ~10-15 fm/c t ideal hydrodynamics

  5. Are hydro results consistent?If not, what does it mean? p p PartialCE elliptic flow HadronicCascade Chem.Eq. PHENIX white paper, NPA757,184(2005) pT spectra

  6. Differential Elliptic Flow Developsin the Hadron Phase? Kolb and Heinz(’04) Is v2(pT) really sensitive to the late dynamics? 100MeV T.H. and K.Tsuda (’02) 140MeV 0.8 1.0 0.2 0.6 0 0.4 0.8 0.2 0.6 0 0.4 transverse momentum (GeV/c)

  7. Mean pT is the Key Generic feature! t t Slope of v2(pT) ~ v2/<pT> Response todecreasing Tth (or increasing t) v2 <pT> v2/<pT> CE PCE t

  8. Accidental Reproduction of v2(pT) v2(pT) v2(pT) At hadronization Chemical Eq. v2 v2 freezeout <pT> <pT> pT pT v2(pT) Chemical F.O. CE: increase CFO: decrease v2 <pT> pT

  9. 1.Why mean pT behaves so differently?2. Why CE result ~ HC result? PartialCE HadronicCascade PHENIX white paper, NPA757,184(2005) Chem.Eq.

  10. For a more rigorous discussion, see T.H. and M.Gyulassy, nucl-th/0506049 Intuitive Picture Mean ET decreases due to pdV work Chemical Freezeout • ETper particle increases • in chemical equilibrium. • This effect delays cooling of the system like a viscous fluid. • Chemical equilibrium imitates viscosity at the cost of particle yield!!! MASS energy KINETIC energy Chemical Equilibrium

  11. Chem. Eq. Imitates Viscosity! Contour(T=const.) T(t) at origin Model CE <vr>(Tth) Model PCE T.H. and K.Tsuda(’02) t

  12. Summary of Hydro Results “No-Go theorem” Ruled out! • WINNER for hydro race at RHIC ! • Hybrid model (Ideal QGP fluid + dissipative hadron gas) by Teaney, Lauret, and Shuryak

  13. The End of 50-Year-Old Ideal, Chem. Eq. Hadronic Fluid After the famous Landau’s paper (1953), ideal and chemical equilibrium hadronic hydrodynamics has been exploited for a long time. However, the model may not be used when chemical freezeout happens earlier than thermal freezeout since it accidentally reproduces pT spectra and v2(pT) at the cost of particle yields in a way that it imitates viscosity.

  14. Digression A Long Long Time Ago… …we obtain the value R (Reynolds number)=1~10… Thus we may infer that the assumption of the perfect fluid is not so good as supposed by Landau.

  15. Summary 1 • Critical data harvested at RHIC • Particle ratio (Particle yield) • pT spectra • v2 AND v2(pT) Hydrodynamic analyses Nearly perfect fluidity of the sQGP core AND Highly dissipative hadronic corona

  16. Part 2 Results from CGC + full 3D hydro + hadronic cascade

  17. T.H. and Y.Nara, PRC66(’02)041901, 68(’03)064902, 69(’04)034908, PRL91(’03)082301, NPA743(’04)305 Toward a Unified Model in H.I.C. Nuclear wave function Parton distribution CGC (a la KLN) Color Quantum Fluid(QS2<kT2<QS4/L2) (x-evolution eq.) Collinear factorized Parton distribution (CTEQ) (MV model on 2D lattice) Transverse momentum Parton production (dissipative process?) Shattering CGC (kT factorization) LOpQCD (PYTHIA) (classical Yang-Mills on 2D lattice) important in forward region? Not covered in this talk Hydrodynamics (full 3D hydro) Parton energy loss (a la Gyulassy-Levai-Vitev) Jet quenching QGP Hadron gas Hadronic cascade (JAM) Recombination Fragmentation Proper time Low pT Intermediate pT High pT

  18. CGC + Full 3D Hydro + Cascade t Hadronic Corona (Cascade, JAM) sQGP core (Full 3D Hydro) z 0 Color Glass Condensate c.f. Recent similar approach by Nonaka and Bass (DNP04,QM05)

  19. v2(h) from CGC + Full 3D Hydro + Hadronic Cascade PHOBOS data: “Triangle shape” prop. to dN/dh Tth=100MeV: “Trapezoidal shape” Typical hydro result Tth=169MeV: Triangle shape!Just after hadronization CGC+hydro+cascade: Good agreement! Perfect fluid sQGP core + dissipative hadronic corona picture works in forward region!

  20. CGC+Hydro+Cascade in Cu+Cu Collisions The effect of rescattering is seen especially near midrapidity.

  21. Predictions for LHCfrom CGC+Hydro+Cascade • No jet components • Need to estimate • systematic error from • Cooper-Frye formula • Monotonic increase is • consistent with previous • work by Teaney et al.

  22. Early Thermalization in Peripheral Collisions at RHIC? • CGC + hydro + cascade • agreement only up to • 15~20% centrality • (impact parameter ~5fm) • Centrality dependence • of thermalization time? • Common t0=0.6fm/c • Semi-central to peripheral collisions: • Not interpreted only by hadronic dissipation • Important to understand pre-thermalization stage • Imcomplete thermalization? (Talk by Borghini)

  23. Part 3 Does the hydrodynamic agreement with experimental data suggest even DECONFINEMENT?! hydro+cascade

  24. Viscosity and Entropy Iso, Mori, Namiki (1959) • Reynolds number R>>1 Perfect fluid where • 1+1D Bjorken flow (Ideal) (Viscous) h : shear viscosity (MeV/fm2) s : entropy density (1/fm3) h/s is a good dimensionless measure to see viscous effects.

  25. What Have We Learned? h : shear viscosity, s : entropy density T.H. and M.Gyulassy (’05) • Absolute value of viscosity • Its ratio to entropy density ! What makes this sudden behavior? DECONFINEMENT

  26. Summary • The sQGP core + the dissipative hadronic corona picture can be established through careful comparison of current hydro results with high precision RHIC data. • This picture is confirmed in forward rapidity region by using a “cutting edge” hybrid model (CGC + full 3D hydro + hadronic cascade). • This picture is manifestation of the sudden change of entropy density at Tc, namely deconfinement!

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