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Di-lepton production in strongly coupled quark gluon plasma

Background and Motivation Di-lepton spectra from HIC Sensitivity to EOS Summary and conclusion arXiv: 1009.3091. Di-lepton production in strongly coupled quark gluon plasma. Jian Deng ( 邓建 ) USTC with Qun Wang, Nu Xu , Pengfei Zhuang 2010-10-19 ATHIC2010 @CCNU. We want to know.

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Di-lepton production in strongly coupled quark gluon plasma

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  1. Background and Motivation • Di-lepton spectra fromHIC • Sensitivity to EOS • Summary and conclusion • arXiv:1009.3091 Di-lepton production in strongly coupled quark gluon plasma JianDeng (邓建) USTC with Qun Wang,Nu Xu, PengfeiZhuang 2010-10-19 ATHIC2010 @CCNU

  2. We want to know Because of confinement, we saw no free quarks. Can we observe QGP directly? we know there is a cross-over from partonic phase to hadronic phase. Electromagnetic signals have their advantages to probe the strongly coupled media.

  3. Di-lepton signal in HIC The dilepton signal is an excellent candidate of the electromagnetic probe. some amazing results opened another window to understand strong interacting matter. NA60 observed a significant excess of pairs above the yield expected from neutral meson decay SPS NA60 96, 162302 (2006) RHIC PHENIX arXiv:0711.2118 A strong broadening but essentially no shift in mass of rho meson spectrum is needed to explain this result

  4. Effective temperature Slope parameter T-eff (MeV) T_eff gives the information of the random thermal motion and the collective flow of the thermal source. The transition to a low-flow region may signal a transition from a hadronic source to a partonic source NA60, PRL100, 022302(2008) Out work is try to understand this results and predict what we will get in higher energy collision such as RHIC.

  5. Heavy Ion Collisions HIC Hadronization and Freeze-out Initial high Q2 interactions Partonic matter - QGP - The hot-QCD Initial conditions Hard scattering production - QCD prediction Interactions with medium - deconfinement/thermalization Initial parton density Initial condition in high-energy nuclear collisions - Color Glass Condensation Cold-QCD-matter, small-x, high-parton density - parton structures in nucleon / nucleus S. Bass By Richard. Heeks; From: http://www.flickr.com/photos/11164709@N06/sets/72157607182199900/

  6. Ideal Hydrodynamics + EOS • Local conservation of net charge and energy-momentum • For perfect fluid • 4+1 equations, 5+1 unknown functions +EOS to complete • EOS is an input to define the relation between energy density, pressure and temperature. • describe: component, dof, interaction…

  7. HG EOS Equation Of State QGP EOS Lattice EOS Mix phase EOS

  8. Di-lepton sources in HIC • Drell-Yan process at pre-equilibrium • Charmonium decay and open charm • Thermal quark anti-quark annihilation in QGP phase • Thermal charged pion annihilation in hadronic phase • Vector mesons, Dalitz decay, …… Di-leptons are emitted inthe whole volume of the fireball, not from surface

  9. dileptonfrom annihilation process • Emission rate in thermal bath: Parameter transformation

  10. Yield as a function of proper time • Lattice EOS • QGP EOS

  11. Invariant mass distribution • QGP EOS • HG EOS • Mix phase EOS • Lattice EOS

  12. p_Tslope: Effective temperature • Two stage of evolution. Lattice • M<1 GeV: RHG . • small T large v • M>1 GeV: QGP. • large T small v • The decline near rho mass reveals a phase transition from partonicphase to hadronic phase. • Teff in the intermediate mass region shows the collectivity developed in the partonicstage.

  13. EOS dependence of slope parameter The magnitude of T_efffitted at large p_T is distinguishable for EOS with/out partonic phase T_eff~0.4Gev with partonic phase T_eff~0.3Gev with hadronic phase only Such behaviors of dileptons are expected to be measured and tested in future experiments

  14. If emission from surface The behavior of Teff and v2 are similar to hadronic signals, no structure to manifest the phase transition

  15. If switch off the radial flow Moderate M, sizeable collective flow is observable. Large M, no flow effect. early emission For small M, flow effect is dominant. At small m_T, collective motion --> T_eff At large m_T, harden the spectra from HG

  16. Summary and Conclusion • Thermal dilepton production from sQGP in HIC at RHIC energy is investigated. • 2+1D ideal hydrodynamic model and different types of EOS are employed in our calculation. • Phase transition from HG to QGP leads to a rich structure for dilepton spectra. • Around M~1GeV, the slope parameter is found sensitive to the EOSand radial flow of the fireball. • Dilepton signals serve as clean probes to the hot and dense medium created in HIC.

  17. Thank you !

  18. EOS dependence of v2(M) • HG EOS • QGP EOS • Lattice EOS • Mix phase EOS

  19. Dilepton from PHENIX Scaled by n_binary, without any medium modification; 1)suppress single lepton by melting D-mesons, 2)suppress pairs by switching off dynamics correlation

  20. Preliminary result

  21. Acceptance in PHENIX

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