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High Energy Nuclear Physics : Theory activities

L. Bravina (UiO) for the heavy-ion theory groups from UiB (leader – L. Csernai) and UiO (leader – L. Bravina). High Energy Nuclear Physics : Theory activities. RECFA meeting (Oslo, 15.05.2009). Current projects:

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High Energy Nuclear Physics : Theory activities

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  1. L. Bravina (UiO) for the heavy-ion theory groups from UiB (leader – L. Csernai) and UiO (leader – L. Bravina) High Energy Nuclear Physics: Theoryactivities RECFA meeting (Oslo, 15.05.2009)

  2. Current projects: Bulk particle production in soft and hard processes; anisotropic flow; equation of state; particle freeze-out; role of resonances; HBT correlations; jet quenching; shadowing ... Models at ourdisposal: Hydjet++, MMM, QGSM, UrQMD

  3. 1. HYDJET++ = HYDJET + FASTMC I. Lokhtin et al., Comput. Phys. Commun. 180 (2009) 779 N. Amelin, … L.B. … et al., Phys. Rev. C 77 (2008) 014903 FASTMC HYDJET HYDJET++ K. Tywoniuk, L.B. et al., Phys. Lett. B 657 (2007) 170

  4. the glauber model • heavy-ion collisions • in each rescattering there is a certain probability for particle production

  5. coherent interaction • the projectile becomes large compared to the target • interacts simultaneously with the whole system • effectively less interaction - shadowing • dramatic change of space-time picture

  6. 2. shadowing: predictions for LHC K. Tywoniuk, L.B. et al., J. Phys. G 35 (2008) 104156 A. Capella, L.B. et al., Eur. Phys. J. C 58 (2008) 437

  7. CIM results: Au+au @ 200 Gev Capella, Bravina, Ferreiro, Kaidalov, Tywoniuk, Zabrodin arxiv: 0712.4333 • weaker comover suppression at forward • weaker recombination at forward • stronger initial state effects! no adjusted parameters!

  8. Soft physics: Elliptic flow • Flow with HYDJET++ model: study of jet influence and resonance decay on flow of different particles. • Jet influence : inverse of mass ordering at pT ≈ 2 GeV • Resonance decay influence: increase of v2.

  9. 3. V2 in HYDJET++ for different types of particles L. B., G. Eyyubova et al., arXiv:0903.5175 The model possesses crossing of baryon and meson branches. Hydrodynamics gives mass ordering of v2

  10. Influence of resonance decays for different types of particles on v2 value L. B., G. Eyyubova et al., arXiv:0903.5175 30% 20% 44% 39%

  11. Protons flow : direct and from Δ decays Pions flow : direct and from Δ decays Because of the kinematics of the decay, protons carry practically the same flow as mother Δ particles while pion flow is shifted to low pT Pions flow : direct and from ω decays Pions flow : direct and from ρ decays

  12. 4. EQUILIBRATION IN THE CENTRAL CELL Kinetic equilibrium: Isotropy of velocity distributions Isotropy of pressure Thermal equilibrium: Energy spectra of particles are described by Boltzmann distribution Chemical equlibrium:Particle yields are reproduced by SM with the same values of

  13. QUARK-GLUON STRING MODEL (QGSM) AND ULTRA-RELATIVISTIC QUANTUM MOLECULAR DYNAMICS (URQMD) Excitation of color neutral strings

  14. EOS: HOW DENSE CAN BE THE MEDIUM? L. B. et al., Phys. Rev. C 78 (2008) 014907 ”Big” cell (V = 5x5x5 fm^3) “Small” cell (V => 0) Dramatic differences at the non-equilibrium stage; after beginning of kinetic equilibrium the energy densities and the baryon densities are the same for ”small” and ”big” cell

  15. EOS IN THE CELL: OBSERVATION OF KNEE temperature vs. chemical potentials L.B. et al., PRC 78 (2008) 014907; E. Zabrodin, L.B. et al, arXiv:0902.4601 S. Ejiri et al., PRD 73 (2006) 054506 Although the “knee” is similar to that in 2-flavor lattice QCD, it is related to inelastic (chemical) freeze-out in the system

  16. 5. Freeze-out at RHIC: UrQMD M.S. Nilsson, ”LHC and beyond” (Lund, Feb. 2009)

  17. freeze-out at RHIC: QGSM M.S. Nilsson , ”LHC and beyond” (Lund, Feb. 2009)

  18. 6. Hanbury-Brown—Twisscorrelations M.S. Nilsson , L.B. et al. (to be submitted) Detector Detector

  19. Non-Identical HBT correlations M.S. Nilsson , L.B. et al. (to be submitted)

  20. 7. Multimodulemodeling (MMM) L. Csernai , talk at SQM’08 (Beijing, Oct. 2008)

  21. flow and freeze-out in MMM

  22. flow and freeze-out in MMM

  23. 8.

  24. A.B. Kaidalov, K.A.Ter-Martirosyan, PLB 117 (1982) N.S.Amelin, L.B., Sov.J.Nucl.Phys. 51 (1990) 133 N.S.Amelin, E.F.Staubo, L.P.Csernai, PRD 46 (1992) 4873 9. QGSM PREDICTIONS FOR PP AT LHC At ultra-relativistic energies: multi-Pomeron scattering, single and double diffraction, and jets (hard Pomeron exchange) Gribov’s Reggeon Calculus + string phenomenology

  25. RAPIDITY AND PT SPECTRA: MODEL VS. DATA Inelastic collisions NSD collisions LHC predictions J. Bleibel, L. B., E. Zabrodin et al., (in progress) Description of both pseudorapidity and transverse momentum distributions seems to be good

  26. PREDICTIONS FOR PP @ LHC QGSM: extended longitudinal scaling in p+p collisions holds

  27. VIOLATION OF KNO SCALING AT LHC High-multiplicity tail is pushed up, whereas maximum of the distribution is shifted towards small values of z At energies below 100 GeV different contributions overlap strongly, whereas at higher energies – more multi-string processes 2 4 6 8 => Enhancement of high multiplicities

  28. Summary and outlook • LHC is a discovery machine for both hard and soft physics in HI collisions • Event generators are an indispensable tool for planing the experiments and analysis of data • => Further development of existing MC generators • HI theory groups in Oslo and Bergen are utilizing it to study : EOS, elliptic flow, particle freeze-out, HBT correlations of unlike particles, particle-jet correlations, heavy quark production in a large pT range, scaling properties

  29. Heavy-iontheory and phenomenology Theory Group at UiO: I.C. Arsene, L. Bravina, G. Eyyubova, R. Kolevatov, M.S. Nilsson, K. Tywoniuk*, E. Zabrodin cooperation with ALICE experimental group other collaborators: FIAS, Frankfurt M. Bleicher, G. Burau, H. Stocker MSU, Moscow I. Lokhtin, L. Malinina*, A. Snigirev LPT, Orsay A. Capella ITEP, Moscow A. Kaidalov, K. Boreskov ITP, Tuebingen J. Bleibel, C. Fuchs, A. Faessler BITP, Kiev Yu. Karpenko, Yu. Sinyukov IGFAE, Santiago de Compostella E.G. Ferreiro, K. Tywoniuk* 21 – papers in international refereed journals 10 – published conference contributions 29 – oral and poster presentations (for 5 years)

  30. Heavy-iontheory and phenomenology Theory Group at UiB: L. Csernai, S. Hotvath, Yun Cheng, M. Zetenyi* cooperation with ALICE experimental group other collaborators: FIAS, Frankfurt I. Mishustin, E. Molnar, D. Rischke Uni.-Minnesota J. Kapusta BNL L. McLerran LANL, Los-Alamos D. Strottman ECM, Barcelona V.K. Magas RMKI, Bud M. Zetenyi* 19 – papers in international refereed journals 7 – published conference contributions 17 – oral and poster presentations (for 5 years)

  31. Back-up Slides

  32. change of space-time picture + + . . . • the diagrams corresponding to ”classical” rescatterings are suppressed at high energies! • Gribov trick: Glauber is OK after all! Almost... • have to take into account diffractive intermediate states!

  33. Freeze-out at RHIC: UrQMD

  34. Freeze-out at RHIC: QGSM

  35. Motivation: ExperimentalResults W. Busza, JPG 35 (2008) 044040 Extrapolation of NSD pp data to LHC using ㏑√s scaling of the width and height of the distribution

  36. Motivation: ExperimentalResults W. Busza, JPG 35 (2008) 044040 e+e－ Example of extended longitudinal scaling in different reactions

  37. HypothesisofFeynmanscaling R. Feynman, PRL 23 (1969) 1415; also in ”Photon-hadron interactions” Basic assumption: scaling of inclusive spectra within the whole kinematically allowed region of xF (or c.m. y) In addition: existence of central area , where is assumed. In terms of rapidity

  38. ConsequencesofFeynmanscaling • Logarithmic rise of the central rapidity region with energy • Fragmentation regions are fixed • Main contribution to mean multiplicity comes from the central area • (5) Contribution from the fragmentation regions is energy independent (4) In the central area particle density does not depend on energy and rapidity

  39. violationofFeynmanscaling UA5 Collab., Phys. Rep. 154 (1987) 247 W. Busza, JPG 35 (2008) 044040 Violation of Feynman scaling, but ext. long. scaling holds?! Charged particle pseudorapidity density at h = 0 as a function of √s

  40. PREDICTIONS FOR P+P @ LHC LHC QGSM: pseudorapidity distribution of particles

  41. VIOLATION OF ELS IN A+A AT LHC? J. Cleymans, J.Struempfer, L.Turko, PRC 78 (2008) 017901 s Statistical thermal model: ELS will be violated in A+A @ LHC. What about p+p ?

  42. WHY SCALING HOLDS IN THE MODEL? Short range correlations In string models both FS and ELS holds in the fragmentation regions

  43. KOBA-NIELSEN-OLESEN (KNO) SCALING Z.Koba, H.B.Nielsen, P.Olesen, NPB 40 (1972) 317 Theyclaim that if Feynman scaling holds, then the multiplicity distribution is independent of energyexcept through the variable Experimental data: KNO scaling holds in hhcollisions up to √s = 53 GeV (ISR)

  44. VIOLATION OF KNO SCALING A.B.Kaidalov, K.A.Ter-Martirosyan, PLB 117 (1982) 247 UA5 Collaboration, Phys. Rep. 154 (1987) 247 N.S.Amelin, L.V.Bravina, Sov.J.Nucl.Phys. 51 (1990) 133 Charged-particle multiplicity distributions in the KNO variables in nondiffractive antiproton-proton collisions at √s = 546 GeV and 53 GeV √s

  45. Correlation radii and space-time structure of the source. cos qx=1-½ (qx)2… exp(-Rx2qx2 –Ry2qy2 -Rz2qz2 -Rxz2qx qz) Rx2 =½ (x-vxt)2, Sensitive to emission time Ry2 =½ (y)2, Rz2 =½ (z-vzt)2Sensitive to longitudinal extent 2 Sensitive to transverse extent In-plane Expanding source Dispersion of emitter velocities  x-p correlation: interference dominated by pions from nearby emitters  Interference probes only a part of the source  Interferometry radii decrease with pair velocity Pt=160 MeV/c Pt=380 MeV/c Rout Rout

  46. Model description of femtoscopy observables“RHIC HBT Puzzle” dN/dt time • p-space observables well-understood within hydrodynamic framework • → hope of understanding early stage • x-space observables not well-reproduced • correct dynamical signatures with incorrect dynamic evolution? • Too-large timescales modeled? • emission/freezeout duration (RO/RS) • evolution duration (RL) Heinz & Kolb, hep-ph/0204061 This picture is borrowed from 2nd Warsaw Meeting on Particle Correlations and Resonances in Heavy Ion Collisions Mercedes López Noriega STAR collab.2003

  47. Expected evolution of HI collision vs RHIC data Bass’02 QGP and hydrodynamic expansion hadronic phase and freeze-out initial state pre-equilibrium hadronization Kinetic freeze out dN/dt Chemical freeze out RHIC side & out radii:2 fm/c Rlong & radii vs reaction plane:10 fm/c 1 fm/c 5 fm/c 10 fm/c 50 fm/c time This picture is borrowed from R. Lednicky talk at Nantes meeting, 2006

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