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in collaboration with: I.Bouras, A. El, O. Fochler, F. Reining, J. Uphoff, C. Wesp, Zhe Xu

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## in collaboration with: I.Bouras, A. El, O. Fochler, F. Reining, J. Uphoff, C. Wesp, Zhe Xu

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**collective and hard phenomena**@RHIC&LHCwithin an unified transport description C. Greiner, Obergurgl, february 2011 in collaboration with: I.Bouras, A. El, O. Fochler, F. Reining, J. Uphoff, C. Wesp, Zhe Xu • early thermalization, viscosity and elliptic flow • dissipative shock waves and Mach Cones • jet quenching … same phenomena? • charming probes**Schematic picture of HIC:**by S.Bass time Hot Plasma: Quark-Gluonic Medium Freeze-Out & Hadronisation: Hadronic medium Decoupling: Observation in a detector**Initial production of partons**minijets color glass condensate string matter**BAMPS: BoltzmannApproachofMultiPartonScatterings**A transport algorithm solving the Boltzmann-Equations for on-shell partons with pQCD interactions new development ggg gg, radiative „corrections“ (Z)MPC, VNI/BMS, AMPT Elastic scatterings are ineffective in thermalization ! Inelastic interactions are needed ! Xiong, Shuryak, PRC 49, 2203 (1994) Dumitru, Gyulassy, PLB 494, 215 (2000) Serreau, Schiff, JHEP 0111, 039 (2001) Baier, Mueller, Schiff, Son, PLB 502, 51 (2001) BAMPS: Z. Xu and C. Greiner,PRC 71, 064901 (2005); Z. Xu and C. Greiner, PRC 76, 024911 (2007)**screened partonic interactions in leading order pQCD**elastic part radiative part J.F.Gunion, G.F.Bertsch, PRD 25, 746(1982) T.S.Biro at el., PRC 48, 1275 (1993) S.M.Wong, NPA 607, 442 (1996) screening mass: LPMsuppression: the formation time Lg: mean free path suppressed!**P.Danielewicz, G.F.Bertsch, Nucl. Phys. A 533, 712(1991)**A.Lang et al., J. Comp. Phys. 106, 391(1993) Stochastic algorithm cell configuration in space D3x for particles in D3x with momentum p1,p2,p3 ... collision probability:**Heavy-ion collision at LHC**BAMPS simulation of QGP phase at LHC at sNN = 2.76 TeV Visualization framework courtesy MADAI collaboration, funded by the NSF under grant# NSF-PHY-09-41373**pT spectra**at collision center: xT<1.5 fm, Dz < 0.4 t fm of a central Au+Au at s1/2=200 GeV Initial conditions: minijets pT>1.4 GeV; coupling as=0.3 simulation pQCD 2-2 + 2-3 + 3-2 simulation pQCD, only 2-2 3-2 + 2-3: thermalization! Hydrodynamic behavior! 2-2: NOthermalization**time scale of thermalization**Theoretical Result ! t = time scale of kinetic equilibration.**distribution of collision angles**at RHIC energies gg gg: small-angle scatterings gg ggg: large-angle bremsstrahlung**Transport Rates**• Transport rate is the correct quantity describing kinetic • equilibration. • Transport collision rates have an indirect relationship • to the collision-angle distribution. Z. Xu and CG, PRC 76, 024911 (2007)**Transport Rates**Large Effect of 2-3 !**Z. Xu and CG,**Phys.Rev.Lett.100:172301,2008. Shear Viscosity h Navier-Stokes approximation relation: h <-> Rtr AdS/CFT RHIC**numerical extraction of viscosity- I**F. Reining Starting from a classical ansatz With the Navier-stokes approximaion velocity profile finite size error**numerical extraction of viscosity- II**C. Wesp Green-Kubo relation: equilibrium fluctuations:**numerical extraction of viscosity- II**C. Wesp some examples**numerical extraction of viscosity- II**C. Wesp perturbative small viscosity …**z**y x Motion Is Hydrodynamic • When does thermalization occur? • Strong evidence that final state bulk behavior reflects the initial state geometry • Because the initial azimuthal asymmetrypersists in the final statedn/df ~ 1 + 2v2(pT) cos (2 f) + ... 2v2**Elliptic Flow and Shear Viscosity in 2-3 at RHIC**2-3Parton cascade BAMPS Z. Xu, CG, H. Stöcker, PRL 101:082302,2008 viscous hydro. Romatschke, PRL 99, 172301,2007 h/s at RHIC: 0.08-0.2**Rapidity Dependence of v2: Importance of 2-3! BAMPS**evolution of transverse energy**Mach Cones in Ideal Hydrodynamics**B. Betz, M. Gyulassy, D. Rischke, H. Stöcker, G. Torrieri Box Simulation • QCD “sonic boom”**Mach Cones in BAMPS**Setup jet Jet has constant mean free path and only momentum in z-direction! Medium Box scenario, no expansion of the medium, massless Boltzmann gas interactions: 2 2 with isotropic distribution of the collision angle**Mach Cones in BAMPS:**Different Viscosities • The results agree qualitatively with hydrodynamic and transport calculations → B. Betz, PRC 79:034902, 2009 • Strong collective behaviour is observed • A diffusion wake is also visible, momentum flows in direction of the jet**Mach Cones in BAMPS:**Different Viscosities**Mach Cones in BAMPS:**Different Viscosities**Mach Cones in BAMPS:**Different Viscosities • The shock front (Mach front) gets broader and vanish with more dissipation • The viscosity smears the profile out, but does it affect the Mach angle?**Hard probes of the medium**• nuclear modification factor relative to pp (binary collision scaling) • experiments show approx. factor 5 of suppression in hadron yields high energy particles are promising probes of the medium created in AA-collisions QM 2008, T. Awes**transport model: incoherent treatment ofggggg processes**• parent gluon must not scatter during formation time of emitted gluon • discard all possible interference effects (Bethe-Heitler regime) p1 p2 kt kt lab frame CM frame t = 1 / kt • total boost LPM-effect O. Fochler**Energy Loss in gg ggg Processes**Cross sections ( T = 400 MeV) Energy loss in single gg ggg • Reasonable partonic cross sections over the whole energy range. • Definition of the energy loss DE matters • DE = Ein – max( Eiout ) • DE = w**Gluon Radiation and Energy Loss**Radiaton spectrum (E = 50 GeV) DE distribution (E = 400 GeV) • Heavy tail in DE distribution leads to large mean <DE>**Some BAMPS Events (CM frame)**DE = 0.67 GeV DE = 206.43 GeV DE = 26.01 GeV DE = 117.01 GeV**Quenching of jets**first realistic 3d results with BAMPS RAA ~ 0.052 cf. S. Wicks et al. Nucl.Phys.A784, 426 nuclear modification factor central (b=0 fm) Au-Au at 200 AGeV O. Fochler et al PRL102:202301:2009**Non-Central RAA and High-pT Elliptic Flow**O. Fochler, Z. Xu and C. Greiner,PRC82:024907 (2010) Gluonic RAA for b = 0 and b = 7 fm Differential v2 for b = 7 fm • inclusion of light quarks is mandatory ! • … lower color factor • jet fragmentation scheme Experimental v2 from PHENIX,arXiv:0903.4886**Quenching of jets**preliminary • Rates for quarks and gluons are roughly the same! • quark jet in gluon jet conversion • … needs more analysis**Binary processes – RAA and v2?**10 mb, isotropic 2->2: v2 is still to low 10 mb, isotropic 2->2: jet quenching is already to strong**Sensitivity on the LPM Cut-Off**RAA for different X (b = 7 fm) v2 for different X (b = 7 fm)**charming probes**Heavy flavor in BAMPS e D _ D Initial hardpartonscatterings D D D c Energyloss Charmproduction c c D J/ψdissociation J/ψregeneration c J/ψ Pre-equil. phase c QGP D J/ψ D Jan Uphoff, Fochler, Xu, GreinerPhys. Rev. C 82 (2010) _ _ _ _ _ c c c c c**Initial charm in hard parton scatterings**Three approaches: LO pQCD: mini-jets NLO pQCDDistributions from R. Vogt PYTHIAMonte Carlo Event Generatorfor nucleon-nucleon collisions • both very sensitive on • parton distribution functions • factorization scale • renormalization scale • charm mass**Charm production in the QGP at RHIC**RHIC charm pairs BAMPS maximum of 3.4 pairs are produced J. Uphoff et al.,arXiv:1003.4200 [hep-ph]**Charm production in the QGP at LHC**charm pairs BAMPS LHC November run Large secondary production → Can even be comparable to initial production**Elliptic flow v2 for charm at RHIC**PHENIX, arXiv:1005.1627 J. Uphoff et al., arXiv:1004.4091 [hep-ph] only elastic charm processes**Heavy quark elliptic flow v2 at RHIC**Jan Uphoff can be fixed to by comparing dE/dx to HTL result beyond logarithmic accuracy A. Peshier, arXiv:0801.0595 [hep-ph] P.B. Gossiaux, J. Aichelin,Phys.Rev.C78 (2008)**Heavy quark elliptic flow v2 at RHIC**Peterson fragmentation • Impact of hadronization and decay small PHENIX, arXiv:1005.1627 only elastic processes considered**Heavy quark RAA at RHIC**PHENIX, arXiv:1005.1627 onlyelastic heavy quarkprocesses