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Current Status of QGP ideal hydro + hadronic cascade model

WPCF2010, Kiev, Sept.14-18, 2010. Current Status of QGP ideal hydro + hadronic cascade model. Tetsufumi Hirano The Univ. of Tokyo & LBNL. Collaborators: Pasi Huovinen and Yasushi Nara Prepared for invited review paper in Progress in Particle and Nuclear Physics. Outline. Introduction

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Current Status of QGP ideal hydro + hadronic cascade model

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  1. WPCF2010, Kiev, Sept.14-18, 2010 Current Status of QGP ideal hydro + hadronic cascade model Tetsufumi Hirano The Univ. of Tokyo & LBNL Collaborators: Pasi Huovinen and Yasushi Nara Prepared for invited review paper in Progress in Particle and Nuclear Physics

  2. Outline • Introduction • Model: QGP fluid + hadronic cascade • Results: v2, source function • Prediction: v2 in U+U collisions • Summary

  3. Introduction • Main aim: Understanding RHIC data (mainly flow and a little femtoscopy) based on a systematic analysis with QGP perfect fluid picture • Set a baseline for viscous hydro calculations • After press release of perfect fluid discovery in 2005 Much progress: hadronic dissipation, eccentricity fluctuation, lattice EoS, CGC initial condition and so on.

  4. Model • No single model to understand heavy ion collision. • Employ “cutting edge” modules as far as possible • 3D ideal hydro • Hadronic transport model, JAM • Lattice EoS + resonance gas in JAM • Monte Carlo Glauber/KLN for initial condition

  5. … 20-30% 10-20% 0-10% A Hybrid Approach: Initial Condition hadron gas • Model* • MC-Glauber • MC-KLN (CGC) • epart, eR.P. • Centrality cut time QGP fluid collision axis 0 Au Au *H.J.Drescher and Y.Nara (2007)

  6. Initial Condition w.r.t. Participant Plane Reaction plane Throw a dice to choose b average over events Shift: (<x>,<y>) Rotation:Y Participant plane E.g.) Npartmin= 279 Npartmax= 394 in Au+Au collisions at 0-10% centrality average over events

  7. epart and eR.P. Au+Au Cu+Cu • Eccentricity enhanced due to fluctuation • Significant in small system, e.g., Cu+Cu, perpheal Au+Au • MC-KLN > MC-Glauber * *See, Drescher and Nara, PRC 75, 034905 (2007).

  8. A Hybrid Approach: Hydrodynamics hadron gas • Ideal Hydrodynamics# • Initial time 0.6 fm/c • Lattice + HRG EoS* time QGP fluid collision axis 0 Au Au #Hirano (2002),*Huovinen and Petreczky (2010) + JAM HRG

  9. A Hybrid Approach: Hadronic Cascade hadron gas • Interface • Cooper-Frye formula • at switching temperature • Tsw = 155 MeV • Hadronic afterburner • Hadronic transport • model based on kinetic • theory  JAM* time QGP fluid collision axis 0 Au Au *Y.Nara et al., (2000)

  10. Comparison of Hydro+Cascade Results with Available Data

  11. Filled: PHENIX, PRC69, 034909 (2004), Open: Hydro+cascade From top to bottom, 0-5, 5-10, 10-15, …, 70-80% centrality pT Spectra: MC-Glauber (1) Absolute value of entropy, (2) soft/hard fraction a = 0.18, and (3) switching temperature Tsw = 155 MeV.

  12. Filled: PHENIX, PRC69, 034909 (2004), Open: Hydro+cascade From top to bottom, 0-5, 5-10, 10-15, …, 70-80% centrality pT Spectra: MC-KLN (1) Absolute value of saturation scale and (2) scaling parameters l=0.28 and (3) switching temperature Tsw = 155 MeV

  13. v2(Npart) Au+Au Cu+Cu pT>0 pT>0 MC-Glauber: Apparent reproduction. No room for QGP viscosity? MC-KLN: Overshoot due to larger eccentricity. How small QGP viscosity? PHOBOS, PRC72, 051901 (2005); PRL98, 242302 (2007).

  14. v2(centrality) 0.15 < pT < 2 GeV/c 0.15 < pT < 2 GeV/c Au+Au Cu+Cu • pT cut enhances v2 by ~10% • STAR data in Au+Au corrected by Ollitrault et al.* • v2 w.r.t. participant plane *J.Y.Ollitrault, A.M.Poskanzer and S.A.Voloshin, PRC80, 014904 (2009).

  15. v2(pT) for PID Particles • Results based on MC- • Glauber initialization • Mass splitting pattern OK • A little bit overshoot even • in low pT region •  Centrality dependence • (next slide)? 0-80% In what follows, v2(pT) with MC-KLN will come soon. Stay tuned! PHENIX, PRL91, 182301 (2003)

  16. 0-20% 20-40% 40-60% v2(pT) for PID Particles: Centrality Dependence • Hydro+cascade with • MC-Glauber at work • in 0-20% centrality • Need QGP viscosity • Or, need jet or • recombination/coalescence • components? PHENIX, PRL91, 182301 (2003)

  17. v2(pT) for Charged Particles: Au+Au • Hydro+cascade with MC-Glauber at work in low pT • pT region at work shrinks as moving to peripheral •  Importance of viscosity PHENIX, PRC80, 024909 (2009). STAR, PRC72, 014904 (2005).

  18. v2(pT) for Charged Particles: Cu+Cu • Tendency is the same as that in Au+Au collisions PHENIX, PRL98, 162301 (2007). STAR, PRC81, 044902 (2010).

  19. Source Imaging Source function and emission rate: Inverse problem Koonin-Pratt eq.: Primed (‘) variables in Pair Center-of-Mass System

  20. 1D Source Function for Pions Au+Au, 0-30% 0.3 < kT < 0.9 GeV/c Au+Au, 0-30% 0.3 < kT < 0.9 GeV/c With hadronic rescattering and decays Without hadronic rescattering and decays Non-Gaussian tail in pion source function from hybrid model PHENIX, PRL103, 142301(2009)

  21. 1D Source Function for Kaons Au+Au, 0-30% 0.3 < kT < 0.9 GeV/c Au+Au, 0-30% 0.3 < kT < 0.9 GeV/c With hadronic rescattering and decays Without hadronic rescattering and decays Non-Gaussian tail in kaon source function from hybrid model PHENIX, PRL103, 142301(2009)

  22. Emission Rate for Pions 0-30% Au+Au, pions, 0.3 < px < 0.9 GeV/c Without hadronic rescattering or decays  Negative x-t correlation

  23. Emission Rate for Pions 0-30% Au+Au, pions, 0.3 < px < 0.9 GeV/c With hadronic rescattering and decays  Positive x-t correlation(?)

  24. Emission Rate for Kaons 0-30% Au+Au, kaons, 0.3 < px < 0.9 GeV/c Without hadronic rescattering or decays  Negative x-t correlation

  25. Emission Rate for Kaons 0-30% Au+Au, kaons, 0.3 < px < 0.9 GeV/c With hadronic rescattering and decays  Positive x-t correlation(?)

  26. Predictions from Hydro+Cascade Model

  27. Collisions of Deformed Nuclei at RHIC • U+U collision in run12 • at RHIC? • More multiplicity • Larger eccentricity • Finite eccentricity at • zero impact parameter • body-body collision • Unable to control • configuration  Need • Monte-Carlo study and • event selection

  28. v2 in U+U Collisions • v2 increases due to deformation of colliding nuclei. • v2/e scales with transverse density. • Maximum transverse density increases only by ~10% • in central U+U collisions.

  29. Prediction at LHC STAY TUNED New predictions come in a month.

  30. Summary • Current status of hybrid approach • Elliptic flow • MC-Glauber initialization gives a reasonable agreement with data in very central collisions. • Results deviate from data as moving away from central collisions. • QGP viscosity? • Source function • Non-Gaussian tail is seen through hadronic rescatterings and decays • U+U collisions • Follow scaling behavior, extend (1/S)dNch/dh by ~10%

  31. BACKUP SLIDES

  32. Event Distributions from Monte Carlo Centrality cut is done according to Npart

  33. Correlation btw. Npart and Ncoll Au+Au U+U Ncoll Ncoll Npart Npart

  34. Eccentricity Fluctuation Adopted from D.Hofman(PHOBOS), talk at QM2006 Yi A sample event from Monte Carlo Glauber model Y0 Interaction points of participants vary event by event. Apparent reaction plane also varies.  The effect is significant for smaller system such as Cu+Cu collisions

  35. Event-by-Event Eccentricity

  36. Comparison of Source Functions Both normalized to be unity

  37. Normalization in PHENIX??? (fm-2)

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