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Collective Flow and Jet Quenching in Heavy Ion Collisions. Zhe Xu, Oliver Fochler, Jan Uphoff, Carsten Greiner. Institut für Theoretische Physik Goethe-Universität Frankfurt, Germany. Prerow, Oct. 13, 2009. Elliptic Flow and Viscous Hydrodynamics.
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Collective Flow and Jet Quenching in Heavy Ion Collisions Zhe Xu, Oliver Fochler, Jan Uphoff, Carsten Greiner Institut für Theoretische Physik Goethe-Universität Frankfurt, Germany Prerow, Oct. 13, 2009
Elliptic Flow and Viscous Hydrodynamics M.Luzum and P. Romatschke, PRC 78, 034915 (2008) Muronga, Huovinen, Song/Heinz,Teaney/Dusling, Molnar/Niemi/Rischke, Chaudhuri, Hama Zhe Xu, Prerow 2009
Jet Quenching and pQCD calculations DGLV cf. S. Wicks et al. Nucl.Phys.A784, 426 Gyulassy, Levai, Vitev, Wang, Baier, Mustafa, Thoma, Armesto, Salgado, Wiedemann, Zapp, Rapp, van Hees, Peshier Zhe Xu, Prerow 2009
Towards a unified understanding of elliptic flow and jet quenching within a pQCD based parton transport Zhe Xu, Prerow 2009
Transport Model BAMPS: BoltzmannApproachofMultiPartonScatterings A transport algorithm solving the Boltzmann-Equations for on-shell partons with pQCD interactions new development ggg gg (Z)MPC, VNI/BMS, AMPT, PACIAE Elastic scatterings are ineffective in thermalization ! Inelastic interactions are needed ! Zhe Xu, Prerow 2009
Stochastic algorithm ZX and C. Greiner,PRC 71, 064901 (2005) y Space is divided into small cells ! x D3x collision probability -- stochastic Zhe Xu, Prerow 2009
screened pQCD based partonic interactions J.F.Gunion, G.F.Bertsch, PRD 25, 746(1982) LPMsuppression: treatment for incoherent interactions: the formation time Lg: mean free path Zhe Xu, Prerow 2009
Results: Transverse Energy in Au+Au at RHIC Initial conditions: gluon minijets production in independent binary NN collisions Zhe Xu, Prerow 2009
Elliptic Flow at RHIC using BAMPS ZX, Greiner, Stöcker, PRL 101, 2008 gg<->ggg processes generate large elliptic flow ! Zhe Xu, Prerow 2009
Cross Sections Zhe Xu, Prerow 2009
distribution of collision angles at RHIC energies gg gg: small-angle scatterings gg ggg: large-angle bremsstrahlung central plateau Zhe Xu, Prerow 2009
ZX and C.Greiner, PRL 100, 172301, (2008) transport rate A. El, A. Muronga, ZX and C. Greiner, PRC 79, 044914 (2009) Zhe Xu, Prerow 2009
Uncertainty: dependence of v2 on freeze-out condition generate the same elliptic flow. Therefore, h/sbetween 0.08 and 0.2. Zhe Xu, Prerow 2009
ZX and C. Greiner, PRC 79, 014904 (2009) • including quarks enhances degrees of freedom • details of hadronisation Zhe Xu, Prerow 2009
v2 at high pT by Oliver Fochler Zhe Xu, Prerow 2009
Jet Quenching – Gluon Energy Loss by Oliver Fochler RAA ~ 0.06 for b=0 O. Fochler, ZX and C. Greiner, PRL 102, 202301 (2009) Zhe Xu, Prerow 2009
Wicks, Horowitz, Djordjevic, Gyulassy Nucl.Phys.A784, 426 (2007) Zhe Xu, Prerow 2009
Elliptic Flow of Charm Quarks by Jan Uphoff Bremsstrahlung gc -> gcg needed? Zhe Xu, Prerow 2009
Conclusion and Outlook Inelastic pQCD based interactions (23 + 32) explain: • LargeCollective Flow • Small shear Viscosity of QCD matter at RHIC h/s: 0.08 ~ 0.2 • Gluon Quenching v2(pt) and v2 do not match data simultanously: need better understanding of quark dynamics and hadronization Need bremsstrahlung for v2(charm) Zhe Xu, Prerow 2009
Elliptic Flow and Shear Viscosity at RHIC viscous hydro. Romatschke, PRL 99, 2007 2-3Parton cascade BAMPS ZX, Greiner, Stöcker, PRL 101, 2008 h/s at the collision center h/s > 0.08 Zhe Xu, Prerow 2009
Including `quarks´ in BAMPS Assume: Quark dynamics is as same as the gluon one. Changing the degrees of freedom of gluons 16 to 40 (gluons+quarks with 2 flavors) Zhe Xu, Prerow 2009
Including `quarks´ 15% effect instead of 26% due to imcomplete chemical equilibration Zhe Xu, Prerow 2009
De Broglie length over mean free path Changing the mean free path by the inverse of the transport rate will lower the ratios. Zhe Xu, Prerow 2009
Y X Understanding of elliptic flow and jet quenching at RHIC P.Huovinen et al., PLB 503, 58 (2001) Zhe Xu, Prerow 2009