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Christoph Blume University of Heidelberg

International School on: Quark-Gluon Plasma and Heavy Ion Collisions: Past, Present, Future Villa Gualino, Turino, Italy Soft Probes II. Christoph Blume University of Heidelberg. Observables. Temperature. Strangeness Resonances. Femtoscopy Fluctuations. Kinetic Freeze-Out.

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Christoph Blume University of Heidelberg

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  1. International School on:Quark-Gluon Plasma and Heavy Ion Collisions:Past, Present, FutureVilla Gualino, Turino, ItalySoft Probes II Christoph Blume University of Heidelberg

  2. Observables Temperature Strangeness Resonances Femtoscopy Fluctuations Kinetic Freeze-Out Chemical Freeze-Out Flow Jets + Heavy Flavor Photons

  3. Strangeness

  4. Strangeness in Heavy Ion Physics Strangeness enhancement as a QGP signature J. Rafelski and B. Müller, PRL48, 1066 (1982) P. Koch, B. Müller, and J. Rafelski, Phys. Rep. 142, 167 (1986) Strangeness has to be produced (no s-Quarks in nucleons) Thresholds are high in hadronic reactions, e.g..: N + N  N + K+ +  (Ethres  700 MeV) Fast equilibration in a QGP via partonic processes, e.g. gluon-fusion ⇒ Enhancement of strange particle production in A+A relative to p+p expected (in particular multi-strange particles)

  5. Statistical Models Multiplicities determined by statistical weights (⇒ chemical equilibrium) Grand-canonical partition function: ⇒ Parameters: V, T, μB, γS Details: see F. Becattini’s lecture A.Andronic et al. PLB673, 142 (2009) F.Becattini et al., PRC69, 024905 (2004)

  6. Pb+Pb@ √sNN = 17.3 GeV UrQMD Hadronic Transport Models Microscopic approach Hadronic degrees of freedom Non-equilibrium Production mechanisms: Measured and parameterized cross sections String-excitation and fragmentation Medium effects, Multi-meson fusion, Mass shifts, ... Examples: UrQMD HSD NEXUS (AMPT) (EPOS) ...

  7. Strange Particles

  8. Strangeness Conservation  s s = Isospin Symmetry  Isospin Symmetry    K+ (us) K- (us) K0 (ds)  (uds) K0 (ds) Major Strangeness Carriers: Kaons and Lambdas  >> >>  (uds)  If baryon density is high

  9. Measurement of Charged Kaons via dE/dx Bethe-Bloch function:

  10. Combination of dE/dx and Time-Of-Flight (TOF)

  11. Weak Decay Topologies V0 Topology (K0s, Λ): Ξ- (Cascade) Ω- Topology:

  12. p + -  - K0 - Strangeness Production in a Pion-Proton Event Associated production:

  13. Strangeness Production in a Heavy Ion Event

  14. Reconstruction via Decay Topology NA49 NA57 NA57

  15. Armenteros-Podolanski Plot

  16. Strangeness Enhancement (SPS) NA57: JPG32, 427 (2006)

  17. Strangeness Enhancement (RHIC) STAR: PRC77, 044908 (2008)

  18. Enhancement Towards Lower Energies √sNN (GeV) Contrary to naive expectation Same behavior for multi-strange particles?

  19. Particle Ratios in p+p: RHIC and LHC Increase of relative strangeness production in p+p with √s ALICE: arXiv:1012.3257

  20. Ξ at Threshold Energies Expectation for statistical model (Andronic et al.) HADES: PRL103, 132301 (2009)

  21. Strangeness Enhancement as QGP Signature ? Is it a dominantly partonic effect or can hadronic processes lead to the same fast equilibration? Multi-meson fusion processes C. Greiner and S. Leupold, J. Phys. G 27, L95 (2001) Dynamic equilibration at the phase boundary? P. Braun-Munzinger, J. Stachel, and C. Wetterich, Phys. Lett. B 596, 61 (2004) Hadronization generally a statistical phenomenon? U. Heinz, Nucl. Phys. A 638, 357c (1998), R. Stock, Phys. Lett. B 456, 277 (1999)

  22. Energy Dependence of K/π Ratios Quite sharp maximum in K+/π+ ratio Indication for phase transition (?) PRC77, 024903 (2008) arXiv:1007.2613

  23. − − / +/ Energy Dependence of Hyperon/π Ratios |y| < 0.4 / -/  = 1.5 (+ + -) |y| < 0.5 PRC78, 034918 (2008)

  24. Maximum of Relative Strangeness Production

  25. Chemical Freeze-Out Curve

  26. Chemical Freeze-Out in the QCD Phase Diagram

  27. Spectra

  28. Rapidity Distributions ... BRAHMS: Au+Au, √sNN = 200 GeV

  29. Landau ... p+p Data Pion production ~ Entropy Isentropic expansion Description of the pion gas as a 3D relativistic fluid Prediction: dN/dy is Gaussian of a width given by: L. D. Landau, Izv. Akad. Nauk. SSSR 17 (1953) 52 P. Carruthers and M. Duong-Van, PRD8 (1973) 859

  30. Landau ... works also for Heavy Ions BRAHMS: PRL94, 162301 (2005)

  31. Width of the Φ Rapidity Distribution Expectation for kaon coalescence K+ + K- → Φ PRC78, 044907 (2008)

  32. Radial Expansion and Transverse Momentum Spectra 1/mT dN/dmT 1/mT dN/dmT mT mT No radial flow: exponential spectrum (p+p collisions) With radial flow: add. boost by expansion (vT) ⇒ blue shifted spectrum

  33. Blast Wave Analysis of Particle Spectra Central Pb+Pb 158A GeV E. Schnedermann and U. Heinz, PRC50, 1675 (1994)

  34. Energy Dependence of Kinetic Freeze-Out arXiv:1007.2613

  35. Energy Dependence of 〈mT〉 NA49: PRC77, 024903 (2008)

  36. Radial Expansion of Strange Particles What about heavy particles (Ξ, Ω, J/ψ) ? NA57: JPG32, 2065 (2006)

  37. Radial Expansion of Strange Particles Particles with low hadronic cross sections: Ξ, Ω, J/ψ ⇒ Not sensitive to flow in hadronic, but maybe to partonic phase N. Xu and M. Kaneta, NPA698, 306 (2002) 306.

  38. Radial Expansion of Strange Particles Multi-strange particles sensitive to the partonic flow contribution (?) STAR: PRL92, 182301 (2004)

  39. Resonances

  40. Resonances Strong decays ⇒ short lifetimes that can be in the order of the fireball lifetime Examples: K(892) → K+ + π - : cτ = 3.91 fm Φ(1020) → K+ + K- : cτ = 46.5 fm Σ-(1385) → Λ + π - : cτ = 5.08 fm Λ(1520) → p + K- : cτ = 12.7 fm Should be sensitive to the late phase of the hadronic fireball Regeneration Rescattering of decay products ⇒ Provide information on the time span between chemical and kinetic freeze-out

  41. Recombination and Rescattering of Resonances Picture adapted from C. Markert and P. Fachini Hot and dense medium Particle yields K* K π π K K Particle spectra π K* Time

  42. Measurement of Resonances: Σ(1385) and Λ(1520) STAR: PRC71, 064902 (2005)

  43. Rescattering after Chemical Freeze-Out STAR: PRC71, 064902 (2005)

  44. Comparison to Chemical Equilibrium Expectation Pb+Pb, √sNN = 17.3 GeV Pb+Pb, √sNN = 17.3 GeV NA49: pub. in preparation HGM: F. Becattini et al.

  45. Scaling Properties of the Φ Meson No scaling with K+ × K- (coalescence picture) Scaling with (s-Quarks)2 Φ = ss K+ ∝ s-Quarks K- + Λ ∝ s-Quarks _ _

  46. K+/π + and Λ/π – Compared to Statistical Model A. Andronic et al., PLB676, 142 (2009)

  47. Energy Dependence of K/π Ratios Quite sharp maximum in K+/π+ ratio Indication for phase transition (?) PRC77, 024903 (2008)

  48. Antibaryon-Baryon Ratios S = -3 S = -2 S = -1 S = 0 NA49: PRC78, 034918 (2008)

  49. Baryon-Meson-Ratios

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