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QGP at RHIC: Seen through Modified Jet Fragmentation

QGP at RHIC: Seen through Modified Jet Fragmentation. Jet. Xin-Nian Wang 王新年 LBNL. CCAST Workshop August 10, 2004. My Collaborators. China: Enke Wang, Benwei Zhang, Hanzhong Zhang US: X.F. Guo, J. Osborne, J. Owens, A. Majumder. Medium Response Function.

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QGP at RHIC: Seen through Modified Jet Fragmentation

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  1. QGP at RHIC: Seen through Modified Jet Fragmentation Jet Xin-Nian Wang 王新年 LBNL CCAST Workshop August 10, 2004

  2. My Collaborators • China: • Enke Wang, Benwei Zhang, Hanzhong Zhang • US: • X.F. Guo, J. Osborne, J. Owens, A. Majumder

  3. Medium Response Function Dynamic System: Photon or dilepton emission (space-like photon) J/Y suppression QCD Response: Parton scattering & dE/dx

  4. Jet Quenching & Modified Jet Fragmentation parton hadrons E ph Suppression of leading particles (Huang, XNW’96) Dh/a(z)=dN/dz (z=ph/E) How to measure dE/dx ? • Modification of fragmentation function Fragmentation Function are measured, and its QCD evolution tested in e+e-, ep and pp collisions

  5. DIS off Nuclei e- Frag. Func.

  6. Parton Fragmentation Function q S e+e- annihilation

  7. DGLAP Evolution Splitting function

  8. DGLAP Evolution 0.075 0.15 Binnewies, Kniehl, Kramer 1995 0.25 0.35 0.5 0.75 z=0.9

  9. Multiple Parton Scattering Formation time

  10. Modified Fragmentation Modified splitting functions Two-parton correlation: LPM Guo & XNW’00

  11. Parton Energy Loss BDPM Gyulassy Vitev Levai Wang & Wang Wiedemann; Zakharov Quark energy loss = energy carried by radiated gluon

  12. HERMES data E. Wang & XNW PRL 2000 in Au nuclei

  13. High pT spectra in A+A collisions pQCD Parton Model

  14. High pt spectra in pp collisions H. Zhang J. Owens E. Wang XNW 2004

  15. High pt spectra in Au+Au H. Zhang E. Wang J. Owens XNW 2004, in preparation

  16. Single hadron suppression

  17. Suppression of away-side jet Df

  18. Azimuthal anisotropy I Single hadron

  19. Di-hadron fragmentation function h1 h2 jet

  20. DGLAP for Dihadron Fragmentation h1 h1 h2 h2 h1 h2

  21. Comparison with Monte Carlo

  22. Medium Modification Triggering h1 D(z1,z2)/D(z1)

  23. Modification due to recombination h h ? Hwa & Yang h work in progress

  24. Flavor of Jet Quenching Parton recombination

  25. Criteria for Discovery of QGP Open system, expanding, short-lived, small volume • Criteria: • High density: e>>ec • Large volume: V>>l (mean-free-path) • Long life-time: t>>l • Local thermal equilibration (interaction): approximately • parton degrees of freedom • Debye screening of strong interaction: deconfinement

  26. High density at RHIC GeV for E=10 GeV Consistent with estimate of initial condition From RHIC high pT data: single & di-hadron, v2 Initial (energy) density 30 (100) times of that in a Cold Au Nucleus also consistent with hydrodynamic analysis of radial flow from

  27. Thermalization • Jet quenching • Single and dihadron suppression • Thermalization of hadrons in away-side jet • Elliptic flow • Requires early thermalization • tth<1 fm/c (U. Heinz) • Good agreement with ideal fluid hydro • Hadron chemical composition

  28. Partonic d.o.f. and Deconfinement • Parton recombination effect • Reverse ordering of RAA and v2 • Qualitatively model independent • Deconfinement • J/y suppression (sufficient?)

  29. Summary • Discovery of Jet Quenching at RHIC proves that a interacting dense matter is formed: Opaque to jets • Jet quenching is caused by partonic energy loss • Dense matter at RHIC is 30 times higher than cold nuclei, energy density is 100 times higher • Collective behavior: Hydrodyamic limit strongly interactive QGP • Jet tomography become useful and power tool for studying properties of dense matter

  30. Future Perspective • Beginning of jet tomography study • Details of modified fragmentation • Heavy quark fragmentation • Dihadron fragmentation • Jet-gamma events • Measurements of rare events • J/y suppression • Dilepton and direct photon production

  31. A Perfect Fluid ? Hydrodynamic model with zero viscosity String theory AdS5/CFT Policastro,Son,Starinets Weakly colored Bound states

  32. Bulk Elliptic Flow Hydro-dynamics calc. Pressure gradient anisotropy

  33. Parton Energy Loss Same-side jet profile Same-side jet cone remains the same as in pp collision Hadron rescattering will change the correlation Between leading and sub-leading hadrons

  34. Effect of Hadron Absorption h h Uncertainty principle: For protons Hadron formation time:

  35. Geometry of Heavy Ion Collisions EZDC z x y Impact Parameter (b) ET Centrality of the collisions ET EZDC

  36. No jet quenching in d+Au Initial state effect: Shadowing & pt broadening: XNW, PRC61(00)064910

  37. Azimuthal Anisotropy II STAR preliminary out-plane 20-60% In-plane 20-60% Azimuthal Mapping of jet quenching

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