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Flow and Femtoscopy from QGP Hydro + Hadronic Cascade

Flow and Femtoscopy from QGP Hydro + Hadronic Cascade. Tetsufumi Hirano Dept. of Physics The Univ. of Tokyo. WPCF, Aug. 1-3, 2007. Outline. Part 1 Mass ordering of v 2 (p T ) revisited Violation of mass ordering for f mesons Part 2 Source functions from hydro + cascade 1D

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Flow and Femtoscopy from QGP Hydro + Hadronic Cascade

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  1. Flow and Femtoscopy from QGP Hydro + Hadronic Cascade Tetsufumi Hirano Dept. of Physics The Univ. of Tokyo WPCF, Aug. 1-3, 2007

  2. Outline • Part 1 • Mass ordering of v2(pT) revisited • Violation of mass ordering for f mesons • Part 2 • Source functions from hydro + cascade • 1D • 3D (rside, rout, rlong)-directions • Summary TH, U.Heinz, D.Kharzeev, R.Lacey, and Y.Nara (in preparation)

  3. Is Mass Ordering of v2(pT) a Direct Signal of Perfect Fluidity? STAR white paper (’05) PHENIX white paper (’05) Lines: Results from Ideal hydro

  4. Motivation To understand the QGP in H.I.C., need to understand the hadronic stage since Indispensable to disentangle these effects for understanding of unknowns.

  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 • Mass ordering behavior • results from hadronic • rescatterings. • Not a direct signal of “perfect fluid QGP” b=7.2fm TH et al. (in preparation).

  11. What happens to strangeness sector?

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

  13. 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).

  14. 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).

  15. Summary of flow part • A QGP fluid with hadronic rescattering • Reproduction of v2(pT,m) A hybrid model works well. • Origin of mass ordering of v2(pT) Radial flow effect, not “mass effect”. • Violation of mass ordering for phi mesons • Mass ordering itself is not a direct signal of perfect fluidity!

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

  17. 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-))

  18. 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)

  19. 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

  20. 1D Source Function from Hydro + Cascade (contd.) KT dependence Centrality dependence lambda=1.0 0.2< KT <0.36 GeV/c b=5.8fm lambda = 1.0 Almost no KT dependence Sensitive to impact parameter

  21. 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

  22. 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?

  23. Outlook • Pair-angle dependence of source function in non-central collisions • Other pairs (K, p, …) • Just get started. Many other things to do…

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