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Space-time Evolution of Bulk QCD Matter at RHIC

Space-time Evolution of Bulk QCD Matter at RHIC. Chiho NONAKA Nagoya University. Contents Introduction Hydrodynamic models at RHIC Freezeout process, finite state interactions 3D hydro+UrQMD Results Single particle spectra, reaction yinamics, elliptic flow Summary.

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Space-time Evolution of Bulk QCD Matter at RHIC

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  1. Space-time Evolution of Bulk QCD Matter at RHIC Chiho NONAKA Nagoya University • Contents • Introduction • Hydrodynamic models at RHIC • Freezeout process, finite state interactions • 3D hydro+UrQMD • Results • Single particle spectra, reaction yinamics, elliptic flow • Summary In collaboration with Steffen A. Bass (Duke University & RIKEN BNL) June 7@RHIC AGS annual users’ meeting

  2. Success of Perfect Hydrodynamic Models at RHIC Single particle spectra Huovinen, Kolb, Heinz, Hirano, Teaney, Shuryak, Hama, Morita, ……. Strong elliptic flow Strong coupled (correlated) QGP • However…. • Elliptic flow vs.  Hirano and Tsuda, PRC66 Discrepancy at large : • Insufficient thermalization? • Viscosity effect? • Simple freezeout process? • freezeout • viscosity Hydrodynamic Models at RHIC Huovinen et.al, PLB503 at mid rapidity

  3. Freezeout process in Hydro • Single freezeout temperature? • Difference between chemical andthermal freezeout Heinz,NPA • chemical freezeout • statistical model • Tch ~170 MeV • hadron ratio • thermal freezeout • hydro • Tf ~ 110~140 MeV • Possible solutions: • Partial chemical equilibrium (PCE) • Hirano, Kolb, Rapp • Hydro + Micro Model • Bass, Dumitru, Teaney, Shuryak

  4. Final State Interactions Thermal model T = 177 MeV  = 29 MeV UrQMD 3D-Hydro +UrQMD 2. In UrQMD final state interactions are included correctly. Markert @QM2004

  5. UrQMD • Full 3-d Hydrodynamics • EoS :1st order phase transition • QGP + excluded volume model Hadronization Cooper-Frye formula final state interactions Monte Carlo TC TSW t fm/c 3D-Hydro + UrQMD Model Bass and Dumitru, PRC61,064909(2000) Teaney et al, nucl-th/0110037 • Hadron phase: viscosity effect • Freezeout process: • Chemical freezeout & thermal freezeout • Final state interactions 3D-Hydro +UrQMD Key: • Treatment of freezeout is determined by mean free path. • Brake up thermalization: viscosity effect TC:critical temperature TSW:Hydro  UrQMD

  6. nucleus nucleus 3-D Hydrodynamic Model • Relativistic hydrodynamic equation • Baryon number conservation • Coordinates • Lagrangian hydrodynamics • Tracing the adiabatic path of each volume element • Effects of phase transition on observables • Computational time • Easy application to LHC • Algorithm • Focusing on the conservation law energy momentum tensor Lagrangian hydrodynamics Flux of fluid

  7. 0=0.6 fm/c max=40 GeV/fm3, nBmax=0.15 fm-3 0=0.5 =1.5 Parameters • Initial Conditions • Energy density • Baryon number density • Parameters • Flow • Switching temperature • longitudinal direction • transverse plane Different from Pure Hydro ! vL=Bjorken’s solution); vT=0 TSW=150 [MeV]

  8. PT spectra • PT spectra at central collisions

  9. PT Spectra (Pure Hydro) Tf=110 MeV normalization of p: ratio at Tchem Heinz and Kolb, hep-ph/0204061

  10. Rapidity Distribution • Impact parameter dependence of rapidity distributions

  11. Centrality Dependence • Impact parameter dependence of PT

  12. PT Spectra for Strange Particles Normalization is perfect!

  13. decay Reaction Dynamics • At mid rapidity • Slope becomes steeper

  14. Final State Interactions p, : flatter, pion wind : small cross section

  15. Hydrodynamic expansion final state interaction <PT> vs mass • At mid rapidity

  16. Distribution of # of Collisions • p,  broad • p ~ 10 times,  ~ 7 times •  small cross section

  17. Distribution of # of Collisions • plateau • -3 <  < 3 • flavor difference

  18. f Distribution • , K: peak ~ 19 fm • p, : peak ~ 22 fm • Multistrange particles • small • Species dependence • Broad distribution

  19. f Distribution of M • Final state interactions •  • Duration of • freezeout process

  20. f Distribution of B • Final state interactions •  • Duration of • freezeout process

  21. Collision Rate • MM is dominant.

  22. v2 in hadron phase ? • Quark number scaling of v2 v2: early stage of expansion

  23. Reaction Dynamics in v2 I

  24. Reaction Dynamics in v2 II • Hydro+decay • ~ Hydro@TSW • v2 grows in hadron • phase a bit. • v2 builds up in QGP • phase.

  25. Summary • We present the 3-D hydrodynamic +cascade model • 3-D Hydrodynamic Model • Single particle distribution • Centrality dependence • Elliptic flow • Low Tf : single spectra, elliptic flow, hadron ratios Necessity of improvement of freezeout process in Hydro • 3-D Hydro + UrQMD • Single particle distribution • Centrality dependence • Elliptic flow • Different initial conditions from pure Hydro • Hadron ratios Switching temperature from Hydro to UrQMD • Reaction dynamics in UrQMD • ,small cross section, v2:improvement at forward/backward  • Work in progress • EoS dependence: ex. lattice QCD • Switching temperature dependence

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