1. Collective Flow and Energy Loss with parton transport in collaboration with: I.Bouras, A. El, O. Fochler, F. Reining, J. Uphoff, C. Wesp, Zhe Xu - viscosity and its extraction from elliptic flow - jet quenching … same phenomena? - dissipative shocks and Mach Cones - charm quarks C. Greiner WISH 2010, Catania, september 2010

2. BAMPS: B oltzmann A pproach of M ulti P arton S catterings 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)

3. 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) screened partonic interactions in leading order pQCD screening mass: LPM suppression : the formation time  g : mean free path radiative part elastic part suppressed!

4. Stochastic algorithm P.Danielewicz, G.F.Bertsch, Nucl. Phys. A 533, 712(1991) A.Lang et al., J. Comp. Phys. 106, 391(1993) for particles in  3 x with momentum p 1,p 2,p 3... collision probability: cell configuration in space 3x3x

5. Simulation: parton cascade

6. 3-2 + 2-3: thermalization! Hydrodynamic behavior! 2-2: NO thermalization simulation pQCD 2-2 + 2-3 + 3-2 simulation pQCD, only 2-2 at collision center: x T <1.5 fm,  z < 0.4 t fm of a central Au+Au at s 1/2 =200 GeV Initial conditions: minijets p T >1.4 GeV; coupling  s =0.3 p T spectra

7. gg  gg: small-angle scatterings gg  ggg: large-angle bremsstrahlung distribution of collision angles at RHIC energies

8. Shear Viscosity  Navier-Stokes approximation relation:  R tr Z. Xu and CG, Phys.Rev.Lett.100:172301,2008. RHIC AdS/CFT

9. ...extracting viscosity Finally we find Starting from a classical ansatz With the Navier-stokes approximaion We find a velocity profile F. Reining

10. ...extracting viscosity C. Wesp Green-Kubo relation: equilibrium fluctuations:

11. Motion Is Hydrodynamic x y z When does thermalization occur? –Strong evidence that final state bulk behavior reflects the initial state geometry Because the initial azimuthal asymmetry persists in the final state dn/d  ~ 1 + 2 v 2 (p T ) cos (2  ) +... 2v 2

12. Elliptic Flow and Shear Viscosity in 2-3 at RHIC 2-3 Parton cascade BAMPS Z. Xu, CG, H. Stöcker, PRL 101:082302,2008 viscous hydro. Romatschke, PRL 99, 172301,2007  /s at RHIC: 0.08-0.2

13. Rapidity Dependence of v 2 : Importance of 2-3! BAMPS evolution of transverse energy

14. … looking on transverse momentum distributions gluons are not simply pions … need hadronization (and models) to understand the particle spectra

15. … and adding quarks as further degrees of freedom quarks are helping in the right direction … Z. Xu and C. Greiner, arxiv:1001.2912

16. nuclear modification factor relative to pp (binary collision scaling) experiments show approx. factor 5 of suppression in hadron yields Hard probes of the medium high energy particles are promising probes of the medium created in AA-collisions QM 2008, T. Awes

17. LPM-effect transport model: incoherent treatment of gg  ggg processes  parent gluon must not scatter during formation time of emitted gluon discard all possible interference effects (Bethe-Heitler regime) ktkt CM frame p1p1 p2p2 lab frame ktkt  = 1 / k t total boost O. Fochler

18. Energy Loss in gg  ggg Processes Reasonable partonic cross sections over the whole energy range. Definition of the energy loss  E matters  E = E in – max( E i out )  E =  Cross sections ( T = 400 MeV) Energy loss in single gg  ggg

19. Gluon Radiation and Energy Loss Heavy tail in  E distribution leads to large mean Radiaton spectrum (E = 50 GeV)  E distribution (E = 400 GeV)

20. Some BAMPS Events (CM frame)  E = 0.67 GeV  E = 206.43 GeV  E = 26.01 GeV  E = 117.01 GeV

21. R AA ~ 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 Quenching of jets first realistic 3d results with BAMPS PRL102:202301:2009

22. inclusion of light quarks is mandatory ! … lower color factor jet fragmentation scheme O. Fochler, Z. Xu and C. Greiner, arxiv:1003.4380 Non-Central R AA and High-p T Elliptic Flow Gluonic RAA for b = 0 and b = 7 fm Differential v 2 for b = 7 fm Experimental v 2 from PHENIX, arXiv: 0903.4886

23. B. Betz, M. Gyulassy, D. Rischke, H. Stöcker, G. Torrieri Mach Cones in Ideal Hydrodynamics Box Simulation QCD “sonic boom”

24. a shock wave travels with a speed higher than speed of sound a rarefaction wave travels to the left with the speed of sound The Relativistic Riemann Problem

25. Riemann problem at finite viscosity Development of a shock plateau I. Bouras et al, PRL 103:032301 (2009)  /s less than 0.1-0.2 Tleft = 400 MeV Tright = 200 MeV t = 1.0 fm/c

26. time evolution of viscous shocks Tleft = 400 MeV Tright = 320 MeV η/s = 1/(4 π) t=0.5 fm/c t=1.5 fm/c t=3 fm/c t=5 fm/c

27. 27 Medium jet Box scenario, no expansion of the medium, massless Boltzmann gas interactions: 2  2 with isotropic distribution of the collision angle Mach Cones in BAMPS Setup Jet has constant mean free path and only momentum in z-direction!

28. 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

29. Mach Cones in BAMPS: Different Viscosities

30. Mach Cones in BAMPS: Different Viscosities

31. 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?

32. Stoped Jet in BAMPS:

36. Initial charm in hard parton scatterings Two approaches: 1.LO pQCD: mini-jets 2.PYTHIA Monte Carlo Event Generator for nucleon-nucleon collisions both very sensitive on parton distribution functions factorization scale renormalization scale charm mass

37. Charm production in the QGP at RHIC charm pairs RHIC BAMPS Maximum charm production of 3.4 pairs J. Uphoff et al., arXiv:1003.4200 [hep-ph]

38. Charm production in the QGP at LHC LHC BAMPS charm pairs

39. Elliptic flow v 2 for charm at RHIC J. Uphoff et al., arXiv:1004.4091 [hep-ph] only elastic charm processes

40. Heavy quark elliptic flow v 2 at RHIC PHENIX, arXiv:1005.1627 A. Peshier, arXiv:0801.0595 [hep-ph] P.B. Gossiaux, J. Aichelin, Phys.Rev.C78 (2008) Jan Uphoff

41. Heavy quark R AA at RHIC PHENIX, arXiv:1005.1627

42. Inelastic/radiative pQCD interactions (23 + 32) explain: fast thermalization large collective flow small shear viscosity of QCD matter at RHIC realistic jet-quenching of gluons Summary Future/ongoing analysis and developments: light and heavy quarks jet-quenching (Mach Cones, ridge) hadronisation and afterburning (UrQMD) needed to determine how imperfect the QGP at RHIC and LHC can be … and dependence on initial conditions dissipative hydrodynamics

43. Semiclassical kinetic theory? Weak or strong …. Validity of kinetic transport - relation to shear viscosity Quantum mechanics: quasiparticles?

44. Energy Loss in a Static Medium Elastic energy loss ~T 2 ln(E / T) Large differential energy loss due to gg  ggg Roughly dE / dx ~ E Rapid evolution of energy spectrum E-spectrum (T = 400 MeV, E 0 = 50 GeV)