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QGP hydro + hadronic cascade model: Status report

QGP hydro + hadronic cascade model: Status report. Tetsufumi Hirano Dept. of Physics The Univ. of Tokyo. TH, U.Heinz, D.Kharzeev, R.Lacey and Y.Nara, PLB636(2006)299; in preparation TH, U.Heinz, work in progress. RCNP, Oct. 29-30, 2007. Outline. Introduction

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QGP hydro + hadronic cascade model: Status report

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  1. QGP hydro + hadronic cascade model: Status report Tetsufumi Hirano Dept. of Physics The Univ. of Tokyo TH, U.Heinz, D.Kharzeev, R.Lacey and Y.Nara, PLB636(2006)299; in preparation TH, U.Heinz, work in progress. RCNP, Oct. 29-30, 2007

  2. Outline • Introduction • Momentum Space (elliptic flow) • Mass ordering of v2(pT) revisited • Violation of mass ordering for f mesons • Soft EOS in CGC case? • Configuration Space (femtoscopy) • Source functions from hydro + cascade • 1D, 3D (rside, rout, rlong)-directions • Summary

  3. Motivation • To understand the QGP in H.I.C., one needs to develop a dynamical framework. • One example of agreement btw. data and theory is not sufficient. (Concerning accidental reproduction) • One needs to improve his/her model continuously toward establishment of • the “observational QGP physics”.

  4. Mechanism of Mass Ordering? STAR white paper (’05) PHENIX white paper (’05) Lines: Results from Ideal hydro

  5. A Hybrid Approach: QGP hydro + hadronic cascade TH et al.(’06) hadron gas • Initial condition: • Transverse  Glauber • Longitudinal  “BGK triangle” • QGP fluid: • 3D ideal hydrodynamics • (Hirano) • massless free u,d,s+g • gas + bag const. • Tc = 170 MeV • Hadron gas: • Hadronic cascade, JAM1.09 • (Nara) • Tsw = 169 MeV time QGP fluid collision axis 0 Au Au (1D) Bass, Dumitru (2D) Teaney, Lauret, Shuryak, (3D) Nonaka, Bass, Hirano et al.

  6. Pseudorapidity Distribution Tune initial parameters with Tth = 100MeV to reproduce dN/deta. Then, switch to hadronic cascade below T=Tsw. Caveat: Rejecting in- coming particles at Tsw

  7. pT spectra for pi, K, and p Reasonable reproduction of yields and spectra in low pT region (pT<~1.5 GeV/c) TH et al. (in preparation).

  8. v2(pT) for pi, K, and p Fail to reproduce data due to (absence of) fluctuation of geometry Miller&Snelling (’03), Bhalerao&Ollitrault(’06) Andrade et al (’06),Drescher&Nara (’07) Browniowski et al(’07) OK! TH et al. (in preparation).

  9. Hydro + Cascade at Work in Forward Rapidity Regions Adapted from S.J.Sanders (BRAHMS) @ QM2006

  10. Origin of Mass Ordering b=7.2fm b=7.2fm • Mass ordering behavior • results from hadronic • rescatterings. • Not a direct signal of “perfect fluid QGP” • Interplay btw. ideal QGP fluid and dissipative hadron gas TH and M.Gyulassy; TH et al. (in preparation).

  11. Why they shift oppositely? pions protons v2(pT) v2 <pT> pT v2 for protons can be negative even in positive elliptic flow must decrease with proper time P.Huovinen et al.,PLB503,58(01); TH et al, in preparation TH and M.Gyulassy, NPA769,71(06)

  12. f MESON FLOW

  13. What happens to strangeness sector?

  14. Additive Quark Model in Transport Codes (JAM/RQMD/UrQMD) For cross sections without exp. data, Expected to be very small for phi, Omega, etc.

  15. Distribution of Freeze-Out Time (no decay) b=2.0fm Early kinetic freezeout for multistrange hadrons: van Hecke, Sorge, Xu(’98) TH et al. (in preparation).

  16. f-meson case Just after hadronization Final results b=7.2fm b=7.2fm T = Tsw = 169 MeV in pT < 1 GeV/c Caveat: Published PHENIX data obtained in pT>~1GeV/c for f mesons This is NOT obtained within ideal hydrodynamics. TH et al. (in preparation).

  17. What happens if f-meson follows radial flow? Of course, mass ordering is seen in hydro calculations

  18. CGC INITIAL CONDITIONS

  19. CGC Initial Condition Glauber-BGK type Color Glass Condensate Transverse profile: Entropy density Longitudinal Profile: Brodsky-Gunion-Kuhn triangle • Unintegrated gluon distribution • a.la. Kharzeev, Levin, and Nardi • Gluon production via kT • factorization formula • Count deposited energy in dV at • (t0,x,y,hs), t0 = 0.6fm/c ene.density ene.density x(fm) x(fm) hs hs

  20. Two Hydro Initial Conditions Which Clear the “First Hurdle” Centrality dependence Rapidity dependence Kharzeev,Levin, and Nardi Implemented in hydro by TH and Nara 1. CGC model Matching I.C. via e(x,y,h) 2.Glauber model (as a reference) Npart:Ncoll = 85%:15%

  21. v2(Npart) from CGC + QGP Fluid + Hadronic Gas Model TH et al.(’06) • Glauber: • Early thermalization • Discovery of Perfect Fluid QGP • CGC: • No perfect fluid? • Additional viscosity • required in QGP Important to understand initial conditions much better for making a conclusion Adil, Gyulassy, Hirano(’06)

  22. Large Eccentricity from CGC Initial Condition y x Hirano and Nara(’04), Hirano et al.(’06) Kuhlman et al.(’06), Drescher et al.(’06) Pocket formula (ideal hydro): v2 ~ 0.2e @ RHIC Ollitrault(’92)

  23. Soft QGP EoS Soft EoS reduces v2 as it should Soft EOS? (equilibrium) or Viscosity? (non-eq.)

  24. Summary of flow part • A QGP fluid with hadronic rescattering • Origin of mass ordering for v2(pT) Radial flow effect, not “mass effect”. • Violation of mass ordering for f mesons • Mass ordering itself is not a direct signal of perfect fluidity! Interplay btw. QGP fluids and hadron gases. • CGC I.C. is “eccentric”. Soft EOS is needed within ideal hydrodynamics.

  25. Femtoscopy from Hydro + Cascade From momentum space to configuration space

  26. Source Imaging Koonin-Pratt eq.: Primed in PCMS (P = 0) Source function and normalized emission rate Source Imaging: Inverse problem from C to D with a kernel K No more Gaussian parametrization! (Brown&Danielewicz (’97-))

  27. Distribution of the Last Interaction Point from Hydro + Cascade x-y x-t • px ~ 0.5 GeV/c for pions • Long tail (w decay? elastic scattering?) • Positive x-t correlation Blink: Ideal Hydro, Kolb and Heinz (2003)

  28. 1D Source Function from Hydro + Cascade KT=PT/2 0.2 < KT <0.36 GeV/c 0.48 < KT <0.6 GeV/c • Angle averaged source function • Broader than PHENIX data • Almost no KT dependence PHENIX data • Significant effects of hadronic rescatterings

  29. Omega Decay or Not? Switch off omega decay by hand in hadronic cascade  Long tail still seen.  Soft elastic scattering of pions? b=5.8fm

  30. 3D Source Function from Hydro + Cascade (preliminary!) side out long • Source function in PCMS • 1fm-slice in each direction • 0.2<KT<0.4 GeV/c, |h| < 0.35, p+-p+, p--p- pairs • Red: Without rescattering, Black: With rescattering • No longer Gaussian shape (Lines: Gaussian) • Broaden by hadronic rescatterings

  31. Summary of Femtoscopy • 1D- and 3D-source functions from a dynamical model (QGP hydro + hadronic cascade) • Significant rescattering effects are seen. • Source function is no longer Gaussian. • Long tail in 1D source function is described within hadronic rescatterings. • KT dependence?

  32. Outlook • Pair-angle dependence of source function in non-central collisions • Other pairs (K, p, L,…) • LL correlation to investigate LL interaction (with Ohnishi-san) • Just get started. Many other things to do…

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