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Dynamical Modeling of Relativistic Heavy Ion Collisions

Dynamical Modeling of Relativistic Heavy Ion Collisions. Tetsufumi Hirano hirano_at_phys.s.u-tokyo.ac.jp http://tkynt2.phys.s.u-tokyo.ac.jp/~hirano.

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Dynamical Modeling of Relativistic Heavy Ion Collisions

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  1. Dynamical Modelingof Relativistic HeavyIon Collisions Tetsufumi Hirano hirano_at_phys.s.u-tokyo.ac.jp http://tkynt2.phys.s.u-tokyo.ac.jp/~hirano Collaborators: M.Gyulassy, Y.Nara, U.Heinz, D.Kharzeev, R.Lacey, T.Gunji, H.Hamagaki, T.Hatsuda, M.Isse, A.Ohnishi, K.Yoshino, R.Mizukawa, N.Akamatsu Oct.19-20, 2007

  2. Introduction Dynamical modeling of heavy ion collisions Bulk Hard/rare probes and interplay btw. soft and hard Summary and Outlook Outline

  3. Phase Diagram of QCD Understanding of phase diagram and EOS is one of the main topics in modern nuclear physics. Taken from http://theory.gsi.de/~friman/trento_06.html

  4. Constraint of EOS from Observation of Compact Stars Model EOS : Pressure as a function of mass-energy density Tolman-Oppenheimer-Volkov eq. (Hydrostatic equilibrium) Observation of compact star mass Mass-Radius relation Taken from Lattimer, Prakash(’06) Taken from Lattimer, Prakash(’06) TOV eq. plays an important role in understanding of EOS

  5. Phase Diagram of QCD Taken from http://theory.gsi.de/~friman/trento_06.html

  6. Constraint of Cosmological Parameters from CMB “Best” cosmological parameters C.L.Bennett et al.,Ap.J.Suppl(’03) Observation COBE, WMAP,… CMB tools: CMBFAST, CAMB, … Taken from http://lambda.gsfc.nasa.gov/ Analysis codes play a major role in precision physics.

  7. Phase Diagram of QCD Taken from http://theory.gsi.de/~friman/trento_06.html

  8. “Mind The Gap” • The first principle (QuantumChromo Dynamics) • Inputs to phenomenology (lattice QCD) Complexity Non-linear interactions of gluons Strong coupling Dynamical many body system Color confinement • Phenomenology (hydrodynamics) ex.)QCDOC • Experimental data • @ Relativistic Heavy Ion Collider • ~150 papers from 4 collaborations • since 2000

  9. Lessons from Other Fields phenomenology people experimental people lattice people • Necessity of collaborative activity in more extended community • Necessity of analysis tool(s) in R.H.I.C. physics • Toward establishment of the “observational QGP physics”

  10. Dynamical Modeling Based on 3D Ideal Hydrodynamics

  11. T.Hirano and Y.Nara(’02-) Current Status of Dynamical Modeling in H.I.C. Geometric Scaling CGC “DGLAP region” Before collisions Transverse momentum Shattering CGC (N)LOpQCD Parton production Pre- equilibrium fluctuation Instability? Equilibration? • Parton energy loss • Inelastic • Elastic Interaction • Hydrodynamics • viscosity • non chem. eq. “Perfect” fluid QGP or GP Recombination Coalescence Dissipative hadron gas Hadronic cascade Fragmentation Proper time Low pT Intermediate pT High pT

  12. BULK • 3D Hydro • 3D Hydro+Cascade • CGC initial conditions

  13. Full 3D Hydro+Cascade Model Hadron gas via hadronic cascade model t QGP fluids via ideal hydrodynamics z Glauber/ Color Glass Condensate 0

  14. TH et al. (’06). Centrality Dependence of v2 • Discovery of “large” v2 at RHIC • v2 data are comparable with hydro results for the first time. • Hadronic cascade models cannot reproduce data. • This is the first time for ideal hydro at work in H.I.C. •  Strong motivation to develop hydro-based tools. AuAu200 Result from a hadronic cascade (JAM) (Courtesy of M.Isse)

  15. TH(’02); TH and K.Tsuda(’02); TH et al. (’06). Pseudorapidity Dependence of v2 AuAu200 • v2 data are comparable with 3D hydro results again around h=0 • Not a QGP gas  sQGP • Nevertheless, large discrepancy in forward/backward rapidity •  See next slides QGP+hadron QGP only

  16. Importance of Hadronic “Corona” AuAu200 • Boltzmann Eq. for hadrons instead of hydrodynamics • Including viscosity through finite mean free path QGP fluid+hadron gas QGP+hadron fluids QGP only Perfect fluid QGP core + Dissipative hadronic corona T.Hirano et al.,Phys.Lett.B636(2006)299. T.Hirano and M.Gyulassy,Nucl.Phys.A769 (2006)71.

  17. Highlights from a QGP Hydro + Hadronic Cascade Model AuAu200 Adapted from S.J.Sanders (BRAHMS) @ QM2006 b=7.2fm 0-50% Works quite well!

  18. TH et al. (in preparation). Origin of Mass Ordering b=7.2fm b=7.2fm Mass ordering behavior comes from hadronic rescattering.  Not a direct signal of “perfect fluid QGP”  Interplay btw. QGP fluid and hadron gas

  19. Sensitivity to Initial Conditions Novel initial conditions from “Color Glass Condensate” lead to large eccentricity. Hirano and Nara(’04), Hirano et al.(’06) Kuhlman et al.(’06), Drescher et al.(’06) Need viscosity/soft EOS in QGP!

  20. Excitation Function of v2 • Hadronic Dissipation • is huge at SPS. • still affects v2 at RHIC. • is almost negligible at LHC.

  21. HARD/RARE PROBES • Hydro+Jet model • Hydro+J/Y model • Interplay btw. soft and hard • Jet-fluid string formation

  22. Utilization of Hydro Results Thermal radiation (photon/dilepton) Jet quenching J/psi suppression charm diffusion Recombination Coalescence Meson c J/psi c Baryon c bar Information along a path Information on surface Information inside medium

  23. Jet Propagation through a QGP Fluid hydro+jet model Color: parton density Plot: mini-jets T.Hirano and Y.Nara (’02-) Full 3D ideal hydrodynamics + PYTHIA Parton distribution fn. pQCD 22 processes Fragmentation Gyulassy-Levai-Vitev formula Inelastic energy loss y Au+Au 200AGeV, b=8 fm transverse plane@midrapidity Fragmentation switched off x

  24. pT Distribution from Hydro+Jet Model Soft + Quenched Hard picture works reasonably well Re/Co components may be needed for a better description Note: Hadronic cascade is switched off in the bulk T.Hirano and Y.Nara, Phys.Rev.C69,034908(2004).

  25. Back-To-Back Correlation Not only energy loss but also deflection are found to be important. T.Hirano and Y.Nara, Phys.Rev.Lett.91,082301(2003).

  26. Gunji, Hamagaki, Hatsuda, Hirano, PRC (in press) Onset of J/Y Melting in a QGP Fluid Hydro+J/Y model J/psi Suppression factor of J/Y c c bar J/Y is assumed to melt away above TJ/y ~ 2Tc Local temperature from full 3D hydro simulations

  27. Heavy Quark Diffusion in a QGP Fluid c c-bar c-bar c v2 is sensitive to relaxation time for heavy quarks in QGP. Toward comprehensive understanding of transport properties of QGP Talk by Akamatsu at KPS meeting yesterday Akamatsu, Hatsuda, Hirano (work in progress)

  28. Hadronization through Jet-Fluid String Formation Space-time evolution of the QGP fluid  Open data table String Fragmentation PYTHIA (Lund) Energy loss  GLV 1st order Hirano, Isse, Nara, Ohnishi, Yoshino, Mizukawa, nucl-th/0702068; (work in progress)

  29. Summary & Outlook • Development of an analysis code in H.I.C. • QGP fluid + hadronic gas picture works well • Sensitivity to initial conditions in hydro • EOS dependence (not discussed in this talk) • Application of hydro results • Single- and di-hadron distributions at high pT • J/Y suppression • Jet-Fluid String formation • (EM probes) • Toward an open and standard tool in H.I.C. (like PYTHIA, CMBFAST, …)

  30. T.Hirano and Y.Nara(’02-) Current Status of Dynamical Modeling in H.I.C. Geometric Scaling CGC “DGLAP region” Before collisions Transverse momentum Shattering CGC (N)LOpQCD Parton production Pre- equilibrium fluctuation Instability? Equilibration? • Parton energy loss • Inelastic • Elastic Interaction • Hydrodynamics • viscosity • non chem. eq. “Perfect” fluid QGP or GP Recombination Coalescence Dissipative hadron gas Hadronic cascade Fragmentation Proper time Low pT Intermediate pT High pT

  31. Thanks!

  32. Dynamics of Heavy Ion Collisions Freezeout “Re-confinement” Expansion, cooling Thermalization First contact (two bunches of gluons) Temperature scale 100MeV~1012K Time scale 10fm/c~10-23sec

  33. T.Hirano and M.Gyulassy,Nucl.Phys.A769 (2006)71. Hadron Gas Instead of Hadron Fluid “Reynolds number” A QGP fluid surrounded by hadronic gas Matter proper part: (shear viscosity) (entropy density) QGP core big in Hadron small in QGP QGP: Liquid (hydro picture) Hadron: Gas (particle picture)

  34. TH and Gyulassy (’06) A Probable Scenario h: shear viscosity, s : entropy density Kovtun,Son,Starinets(’05) • Absolute value of viscosity • Its ratio to entropy density ! QGP fluid at work! Rapid increase of entropy density?! Deconfinement Signal?!

  35. v2(pT) for pi, K, and p Due to fluctuation of geometry OK! TH et al. (in preparation).

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