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Heavy ion collisions at the LHC – theory

Johann Wolfgang Goethe-Universität Frankfurt Institut für Theoretische Physik. Heavy ion collisions at the LHC – theory. C. Greiner. From SPS to RHIC to LHC Tomographic and diagnostic tools Recent theoretical developments: parton cascade , dissipative hydro , classical YM fields

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Heavy ion collisions at the LHC – theory

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  1. Johann Wolfgang Goethe-Universität Frankfurt Institut für Theoretische Physik Heavy ion collisions at the LHC –theory C. Greiner • From SPS to RHIC to LHC • Tomographic and diagnostic tools • Recent theoretical developments: • parton cascade, dissipative hydro, classical YM fields • Summary

  2. CERN • SPS : 1986 - 2003 • S and Pb ; up to s =20 GeV/nucl pair • hadrons, photons and dileptons • LHC : starting 2008 • Pb ; up to s = 5.5 TeV/nucl pair • ALICE and CMS experiments BNL • AGS : 1986 - 2000 • Si and Au ; up to s =5 GeV /nucl pair • only hadronic variables • RHIC : 2000 • Au ; up to s = 200 GeV /nucl pair • hadrons, photons, dileptons, jets

  3. Exploring the phases of nuclear matter

  4. RHIC’s Two Major Discoveries • Discovery of strong “elliptic” flow: • Elliptic flow in Au + Au collisions at √sNN= 130 GeV, STAR Collaboration • 1 citations • Discovery of “jet quenching” • Suppression of hadrons with large momentum in central Au+Au collisions at √sNN = 130 GeV, PHENIX Collaboration • 384 citations

  5. Initial production of partons minijets string matter

  6. LHC multiplicities N. Hammon et al, PRC 61 (2000) 014901 N. Borghini, U.A.Wiedemann, e-Print: arXiv:0707.0564 [hep-ph] 3100 4350 same as lower left plus EKS shadowing Pb+Pb → g Eskola, Kajantie, Z. Phys. C75 (1995) 515 LO pQCD GRV 94, no shadowing p0 = 2 GeV

  7. Saturation approaches Drescher, Nara, arXiv:0707.0249 1800 Kharzeev et al, arXiv:0707.0811 - 2600 2000 Adil, Gyulassy, arXiv:0709.1716 1300 charged particles !(x 3/2 for total mult.) Lesson: dNch/dy ~ 2000: Qs≥ 2 GeV

  8. Momentum space anisotropy Time dependence Michael Strickland

  9. Electromagnetic signals from an anisotropic plasma Use evolving anisotropic momentum space distribution: instant isotropization (hydro) free streaming use interpolating model between these limits: Dilepton yield can be a measure for the isotropization of the plasma Martinez, Strickland, arXiv:0709.3576 Similar for photons: Schenke, Strickland, Phys.Rev.D76:025023,2007.

  10. Colored-Particle-In-Cell (CPIC-) simulation • Numerically solve the Vlasov equation coupled to the Yang Mills equation using a test particle ansatz, leading to the Wong-Yang-Mills equations: Solve using smeared colored particles convergent results with less test particles • Investigate systems (early phase of HIC) that are locally anisotropic in momentum space: A. Dumitru, Y. Nara, M. Strickland Phys.Rev.D75:025016, 2007

  11. Chromo-Weibel-instabilities • In an anisotropic system Weibel instabilities occur due to current filamentation: • Exponential growth of unstable field modes faster isotropization of hard particles • Outlook: inclusion of hard collisions / particle-field conversion / jet physics A. Dumitru, Y. Nara, M. Strickland, Phys.Rev.D75:025016, 2007 B. Schenke, M. Strickland, C. Greiner, M.H. Thoma, Phys.Rev.D73:125004,2006

  12. SU(2) visualization Time Space Michael Strickland

  13. 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

  14. Relativistic Quantum Transport for URHIC RHIC, LHC • microscopic transport calculations of partonic degrees of freedom new development Boltzmann Approach of MultiParton Scatterings (BAMPS) Z. Xu and C. Greiner, PRC 71, 064901 (2005) collision probability D3x particle in cell method

  15. fast isotropization and thermalisation elliptic flow in noncentral Au+Au collisions at RHIC: Z. Xu and C. Greiner, hep-ph/0703233 Z. Xu and C. Greiner, NPA 774, 787 (2006) central hydrodynamical evolution of momentum spectrum, … micr. determination of transport parameter …

  16. Elliptic flow and shear viscosity parton cascade BAMPS (Z. Xu) viscous hydro P. Romatschke,nucl-th/0706.1522

  17. Thermalization time and entropy production Hydrodynamics: Israel-Stewart 2nd order formalism for relativistic viscous hydro: stress relax. time viscosity shear (geom.) Entropy production bound constrains τ0 and η/s Dumitru, Molnar, Nara, arXiv:0706.2203

  18. Dissipative Hydrodynamics Shear, bulk viscosity and heat conductivity of dense QCD matter could be prime candidates for the next Particle Data Group, if they can be extracted from data. Need a causal hydrodynamical theory. What are the criteria of applicability? Causal stable hydrodynamics can be derrived from the Boltzmann Equation: -Renormalization Group Method by Kunihiro/Tsumura-->stable 1st Order linearized BE with f=f0+εf1+ε²f2 yields (2nd Order – work in progress) can be solved by introducing projector P on Ker{A}, where A-linearized collision operator -Grad‘s 14-momentum method-->2nd Order causal hydrodynamics. Calculate momenta of the BE. Transport coefficients and relaxation times for dissipative quantities can be calculated as functions of collision terms in BE. Compare dissipative relaxation times to the mean free pass from cascade simulation. Andrej El

  19. Extra dimension (the bulk) AdS5/CFT Correspondence for Strongly-Coupled Systems • Analogy between black hole physics • and equilibrium thermodynamics • Solutions called black branes • Black branes possess hydrodynamic characteristics • Similar to fluids – viscosity, diffusion constants,…. horizon MULTIPLICITY Entropy  Black Hole Area DISSIPATION Viscosity  Graviton Absorption Use strongly coupled N = 4 SUSY YM theory. Derive a quantum lower viscosity bound: h/s > 1/4p

  20. Au+Au: Systematic Suppression Pattern Enhanced •  constancy for pT > 4 GeV/c for all centralities? Suppressed

  21. BDMPSGLV Jet quenching at the LHC GLV: Phys.Rev.Lett.89 Salgado, Wiedemann: Nucl.Phys.A747 Dainese, Loizides: Eur.Phys.J.C38 CERN-LHCC-2007-009

  22. RAA • angular correlations • energy redistribution • ... Energy loss within BAMPS (Boltzmann Approach to Multi-Particle Scattering) • full transport model • consistent inclusion of inelastic ggggg processes • effective LPM cut-off O. Fochler future investigation of:

  23. Additional near-side long range correlation in  (“ridge like” corrl.) observed. Dan Magestro, Hard Probes 2004, STAR, nucl-ex/0509030, Phys. Rev. C73 (2006) 064907 and P. Jacobs, nucl-ex/0503022 Explaining the “ridge” Au+Au 0-10% STAR preliminary J. Putschke, QM2006 Stronger longitudinal broadening caused by domains of strong chromo-fields with Dumitru, Nara, Schenke, Strickland e-Print: arXiv:0710.1223 [hep-ph]

  24. Jet propagation Dynamical simulation of jet propagation in the plasma preliminary Poynting vectors Björn Schenke

  25. Fluid Effects on Jets ? • Mach cone? • Jets travel faster than the speed of sound in the medium. • While depositing energy via gluon radiation. • QCD “sonic boom” • To be expected in a dense fluid which is strongly-coupled

  26. High pT Parton  Low pT “Mach Cone” • The “disappearance” is that of the high pT partner • But at low pT, see re-appearance • and • “Side-lobes”(Mach cones)

  27. Mach Cones in Ideal Hydrodynamics Barbara Betz, Dirk Rischke, Horst Stöcker, Giorgio Torrieri Box Simulation Bjorken Expansion

  28. AdS/CFT vs. pQCDtested by heavy quark energy loss Horowitz, Gyulassy: arxiv:0706.2336 heavy quark suppression at LHC from pQCD and AdS/CFT AdS/CFT  drag coefficient on heavy quarks in a strongly-coupled SYM plasma

  29. Unexpected Event Characteristics … Micro Black Holes at Colliders Dimopoulos, Landsberg, PRL (2001) Eardley, Giddings, PRD (2002) Bleicher, Hossenfelder, Stöcker, PLB(2002) Yoshino, Nambu, PRD (2003) • Conjecture: Large Extra Dimensions • LHC will produce 100 (1) BH per second in pp (Au+Au) reactions at full energy • For microscopicBHs, t ~ (MBH)3 ~ 10-27 s, decays are essentially instantaneous • TH ~ 1/RBH ~ 100-300 GeV, so not just photons: q,g : l : g : n,G = 75 : 15 : 2 : 8 • Multiplicity ~ 5-20 • Spherical events with leptons, many quark and gluon jets De Roeck (2002)

  30. v2 - scaling law recombination at hadronisation?

  31. Statistical hadronization of charmonium statesJ/Y: suppression at SPS/RHIC to enhancement at LHC J/Y yield at LHC charm production cross section at LHC Andronic et al., Nucl.Phys.A789:334-356

  32. Hagedorn gas close to • Hagedorn spectrum: • master equation: J. Noronha-Hostler, C. Greiner, I. A. Shovkovy.

  33. Rapid kaon and baryon/antibaryon production J. Noronha-Hostler, C. Greiner, I. Shovkovy. (In Preparation)

  34. Conclusions and Outlook • Understanding the(perturbative and nonperturbative) QCD phenomena and properties of the QGP demands real time dynamics and full scope simulations of heavy ion collisions • Understanding the very early stage of the reaction calls for a unified description of classical chromo fields and particles • …the road of dissipative relativistic hydrodynamics • What about hadronization and confinement …

  35. at SPS ??? at RHIC Expansion velocity  s~ 0.8 at SPS ~ 0.5 c at SPS ~0.7 at RHIC  s~ 1 at RHIC mB ~ 250 at SPS mB ~ 50 at RHIC jets

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