1. Dilepton production in UHIC as probe to dense matter Qun Wang Univ of Sci & Tech of China (USTC) J.Deng, QW, N.Xu, P.-f. Zhuang, PLB701,581(2010); H.-j. Xu, H.-f. Chen, X. Dong, QW, Y.-f. Zhang, arXiv:1110.4825 Critical Point and Onset of Deconfinement (CPOD) at CCNU, Wuhan, Nov 7-11, 2011 1Qun Wang (USTC), CPOD'11

2. Outline 1.Background information of dilepton production 2.Hydrodynamics simulation of space-time history of fireball 3.Vector meson contribution 4.T_eff as probe to EOS of dense matter 5.Comparison with STAR data 6.Summary and conclusion 2Qun Wang (USTC), CPOD'11

3. Outline γ q q-bar l+ l- l+ l- meson γ ρ 3Qun Wang (USTC), CPOD'11

4. Dilepton invariant mass spectra 1. Electromagnetic probe to hot/dense medium 2. Chiral symmetry restoration ? 3.Space-time evolution of fireball 4. Drell-Yan,Charmonium, open charm,q-qbar in QGP, Pion-pion in HG via vector mesons, Dalitz decays, 4-pion, …… McLerran & Toimela, ’85 Rapp & Wambach, 00’ Van Hees & Rapp, 06’, 08’ Ruppert et al, 08’ Yi-fei Zhang’s talk 4Qun Wang (USTC), CPOD'11

5. Effective temperature Slope parameter T-eff (MeV) The transition to a low-flow region may signal a transition from a hadronic source to a partonic source NA60, PRL100, 022302(2008) 5Qun Wang (USTC), CPOD'11

6. Di-lepton spactra by PHENIX Problem at low mass region (???) 6Qun Wang (USTC), CPOD'11

7. Strategy Dilepton production in Au+Au collisions at 200 GeV in IMR, QGP phase: q-qbar annihilation; Hadron phase: vector meson selfenergy with vertices involving all mesons below 1300 GeV Space-time evolution of medium is described by a 2+1 ideal hydro model, different EOS are used for hydro Slope parameters and elliptic flows show distinct features from two phases Comparison to recent STAR data 7Qun Wang (USTC), CPOD'11

8. Dilepton emission rate (1) Space-time history encodedu: fluid velocity Photon selfenery (VDM) Imaginary part of Retarded propagator of rho meson In-medium rate 8Qun Wang (USTC), CPOD'11

9. Dilepton emission rate (1) Parameters: g, Λ, G_{ρπX}, G_{ρKK’} from decay width, for example (ρPA vertex) π ρ X = ω,h1(1170) a1(1260), π’(1300) X ρρ K K’(1270) ρ Rapp,PRC 63, 054907 (2001) ωω ρ π π ωωπ π φφ K K-bar 9Qun Wang (USTC), CPOD'11

10. Rho self energy (2) 10Qun Wang (USTC), CPOD'11

11. Rho self energy (3) 11Qun Wang (USTC), CPOD'11

12. Im of rho propagator The imaginary part of the porpagator is sensitive to temperature, but insensitive to its momentum. 12Qun Wang (USTC), CPOD'11

13. Im of ω and φ propagator 13Qun Wang (USTC), CPOD'11

14. Dilepton emission rate (2) transverse velocity of fluid azimuthal angle of fluid slope parameter spectra in transverse momentum and invariant mass differential rate space-time integral 14Qun Wang (USTC), CPOD'11

15. Dilepton emission rate (3) Freezeout hypersurface In-vacuum vector meson propagator Freezeout emission rate Parameters: S95-CE e0=40 GeV/fm^3, τ0=0.4 fm, T0=375 MeV, Tf=128 MeV S95-PCE e0=60 GeV/fm^3, τ0=0.4 fm, T0=413 MeV, Tf=140 MeV 15Qun Wang (USTC), CPOD'11

16. Hydrodynamics for HIC Assumption: thermalization, Ideal or Viscous Inputs: EOS, initial conditions, freeze-out conditions Outputs: space-time evolution Comparison with data: pt-spectra, flows, … Further application: fluctuation & correlation, non- equilbrium statistics,... Baym, Friman, Blaizot et al 86', Rischke 98', Kolb, Huovinen & Heinz, 00-01’, Romatschke, 08’, H. Song & Heinz, 08’, … 16Qun Wang (USTC), CPOD'11

17. Dense or hot QCD matter EOS Bernard et al, (MILC) PRD 75 (07) 094505, Cheng et al, (RBC-Bielefeld) PRD 77 (08) 014511 Bazavov et al, (HotQCD), Phys.Rev.D80:014504,2009 17Qun Wang (USTC), CPOD'11

18. Four equations of state (EOS) Massless ideal QGP Resonance Hadron gas [Braun-Munzinger, Redlich, Stachel, nucl-th/0304013 ] 18Qun Wang (USTC), CPOD'11

19. Time evolution of the rate Differential multiplicity as functions of the dilepton invariant mass and proper time. The lattice EOS is used. The unit is arbitrary. The contributions from QGP and HG are shown in dashed and dotted lines. lattice EOS 19Qun Wang (USTC), CPOD'11

20. Slope parameter: pt and EOS dependence Slope parameter as functions of M for the mixed phase (left panel) and the lattice (right panel) EOS. The results for different values of mT are shown in the solid, dashed and dotted lines. The lines with hollowed circles/triangles are extracted from the HG/QGP components. pt dependenceEOS dependence 20Qun Wang (USTC), CPOD'11

21. Slope parameter: parameter dependence Parameter dependences of the slope parameter with the lattice EOS. Left panel: the initial time for the hydrodynamic evolution τ0= 0.2; 0.6 fm/c. Right panel: the phase transition temperature Tc = 180, 150 MeV. 21Qun Wang (USTC), CPOD'11

22. Elliptic flow v2 and R 22Qun Wang (USTC), CPOD'11

23. Comparison to dilepton data 23Qun Wang (USTC), CPOD'11

24. Transverse momentum spectra 24Qun Wang (USTC), CPOD'11

25. Cocktail of in-medium and freezeout contribution in full space Total = Partonic + In-medium + Freezeout 25Qun Wang (USTC), CPOD'11

26. The semi-leptonic decays of charm hadrons Re-scaled di-electron cross section from charm mesons of semi-leptonic decays in p+p collisions by PYTHIA. Branch ratios from PDG: the nuclear modification factor for nonphotonic electrons in central Au+Au collisions from the PHENIX. 26Qun Wang (USTC), CPOD'11

27. Comparison with STAR preliminary data Comparison with STAR preliminary data in most central (0-10%) Au+Au collisions with the STAR acceptance. 27Qun Wang (USTC), CPOD'11

28. Summary and Conclusion T_eff of di-lepton can serve as a probe to EOS of the dense matter in UHIC Vector meson selfenergy from meson resonances below 1300 MeV are taken into account In-medium and freezeout contributions are identified, charm contribution is modeled Comparison with STAR data is made with good agreement 28Qun Wang (USTC), CPOD'11

29. Thanks! 29Qun Wang (USTC), CPOD'11