1 / 29

Strangeness Dynamics and Transverse Pressure in HIC

Strangeness Dynamics and Transverse Pressure in HIC. Marcus Bleicher Institut für Theoretische Physik Goethe Universität Frankfurt Germany. For further reading….

vilina
Download Presentation

Strangeness Dynamics and Transverse Pressure in HIC

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Strangeness Dynamics andTransverse Pressure in HIC Marcus Bleicher Institut für Theoretische Physik Goethe Universität Frankfurt Germany Marcus Bleicher, Strange Quark Matter 2004

  2. For further reading… • E. L. Bratkovskaya et al, ``Strangeness dynamics and transverse pressure in relativistic nucleus nucleus collisions,'' Phys. Rev. C 69, 054907 (2004) • E. L. Bratkovskaya et al. , ``Strangeness dynamics in relativistic nucleus nucleus collisions,'' Prog. Part. Nucl. Phys. 53, 225 (2004) • M. Bleicher and H. Stocker, ``Dynamics and freeze-out of hadron resonances at RHIC,'' J. Phys. G 30, S111 (2004) • M. Bleicher, ``Probing hadronization and freeze-out with multiple strange hadrons and strange resonances,'' Nucl. Phys. A 715, 85 (2003) • M. Bleicher and J. Aichelin, ``Strange resonance production: Probing chemical and thermal freeze-out in relativistic heavy ion collisions,'' Phys. Lett. B 530, 81 (2002) Marcus Bleicher, Strange Quark Matter 2004

  3. Contents • Chemical equilibrium stage: The ‘horn’, the ‘step’ • Kinetic decoupling stage: Resonance (non-) suppression • Summary Marcus Bleicher, Strange Quark Matter 2004

  4. The tool: UrQMD • Non-equilibrium transport model • Hadrons and resonances • String excitation and fragmentation • Cross sections are parametrizedvia AQM or calculated by detailed balance • Generates full space-time dynamics of hadrons and strings Marcus Bleicher, Strange Quark Matter 2004

  5. Part I: Evidence for the tri-critical point? • 1st Order phase transition at high • No P.T. at low • Search for irregularities around Ebeam = 10-40 GeV: • Flow, strangeness, E-by-E Plot adapted from L. Bravina Marcus Bleicher, Strange Quark Matter 2004

  6. PP Excitation functions • PP works nicely in both models • Pythia used for hard scatterings above 50 GeV Marcus Bleicher, Strange Quark Matter 2004

  7. AA Excitation functions • 4 and mid-y abundancies: OK • Energy dependence: OK • Hadron-string models work well Marcus Bleicher, Strange Quark Matter 2004

  8. Excitation functions: ratios • ‘Horn’ in the ratio not reproduced • well reproduced • relative strange baryon enhancement reproduced Marcus Bleicher, Strange Quark Matter 2004

  9. Ratio excitation functions: Summary • Yields are well reproduced • Most ratios can be understood in transport models • Model K/pi ratios do not reproduce the strong peak observed in data Marcus Bleicher, Strange Quark Matter 2004

  10. Proton-Proton • PP works well • pQCD needed at RHIC • PYTHIA included in • UrQMD 2.x and HSD Marcus Bleicher, Strange Quark Matter 2004

  11. Proton-Nucleus • pA is well under control • What about AA? Marcus Bleicher, Strange Quark Matter 2004

  12. Transverse mass spectra • Standard UrQMD and HSD underestimate the data • Additional resonances from 2-3 GeV may improve the description (UrQMD 2.1) Marcus Bleicher, Strange Quark Matter 2004

  13. Inverse slope systematics • Standard transport models fail • What is missing? • Maybe high mass resonanceslike in UrQMD 2.1 • Maybe Cronin effect at high • energies (HSD) • Maybe initial QGP pressure… Marcus Bleicher, Strange Quark Matter 2004

  14. Hints from elliptic flow 30 AGeV • Data shows saturation of scaled v2 • High mass resonances like in UrQMD 2.1 can not explain v2 above 40 AGeV • Strong hint for initial QGP pressure from 30 AGeV on ! Data for h- Marcus Bleicher, Strange Quark Matter 2004

  15. Phase diagram • QGP might be reachedalready at low SPS energy ! • Tricritical point around 10-40 GeV • No phase transition at RHIC • Necessary to explore 10-30 AGeV energy region to study the phase transition Marcus Bleicher, Strange Quark Matter 2004

  16. Flow excitation functions: Summary • Standard transport models can not describe radial flow • Inclusion of high mass resonances leads to additional flow (maybe necessary at low energies) • Inclusion of Cronin effect leads to additional flow (maybe necessary at high energies) • Assumption of an early QGP phase might create additional flow Marcus Bleicher, Strange Quark Matter 2004

  17. Part II: Probing the late stage of the reaction: Resonances • Is there a (long living) hadronic rescattering stage at SPS and RHIC? • Lifetime of the hadronic stage is measured by resonance absorption/re-feeding • Use different resonances to explore this stage: e.g. mesons: baryons: • Are resonances dissolved in matter? Marcus Bleicher, Strange Quark Matter 2004

  18. π- ρ0 π+ ρ0 ρ0 ρ0 π- π+ π- ρ0 + + + π+ - - - Hadronic vs leptonic channel Au+Au Hot and dense medium Particle yields L* K K p Particle spectra p p L* time Adapted from C. Markert and P. Fachini Marcus Bleicher, Strange Quark Matter 2004

  19. Statistical model fitting • Particle ratios well reproduced • Resonance ratios not reproduced (Braun-Munzinger, QM 2004) • too low • K*/K too high Kai Schweda et al., QM 2004 Marcus Bleicher, Strange Quark Matter 2004

  20. Yields and scaling in AA Baryon resonances: Meson resonances: Yields Ratios All ratios a smooth, no sudden resonance disappearance Marcus Bleicher, Strange Quark Matter 2004

  21. Baryon resonances at RHIC All decaying resonances Finally observed resonances Au+Au, 5% Signal loss due to rescattering of daughters Marcus Bleicher, Strange Quark Matter 2004

  22. Meson resonances at RHIC All decaying resonances Finally observed resonances Au+Au, 5% Note that yields information about all decays (l.h.s), while yields information about r.h.s. Marcus Bleicher, Strange Quark Matter 2004

  23. What about the centrality dependence? • Where is the suppression? • K*/K deceases! • stays constant! Au+Au Calculation by P. Fachini Marcus Bleicher, Strange Quark Matter 2004

  24. Data vs. models Thermal model [1]: T = 177 MeV mB = 29 MeV Life time [fm/c] :  (1020) = 40 L(1520) = 13 K(892) = 4 ++ = 1.7 r (770) = 1.3 UrQMD [2] [1] P. Braun-Munzinger et.al., PLB 518(2001) 41 D.Magestro, private communication [2] Marcus Bleicher and Jörg Aichelin Phys. Lett. B530 (2002) 81. M. Bleicher and Horst Stöcker .Phys.G30 (2004) 111. Rescattering and refeeding are needed rather long living hadron stage From C. Markert Marcus Bleicher, Strange Quark Matter 2004

  25. Tch freeze-out Tkin freeze-out How can we understand these differences? STAR data • Strong decrease in kinetic freeze-out temperature from peripheral to central • Kinetic freeze-out as low as 80 - 90 MeV • Consequences for resonance re-feeding Marcus Bleicher, Strange Quark Matter 2004

  26. Estimate of re-feeding prob. Estimate of available energy for re-feeding at different reaction stages: • can re-created until end of the reaction • re-creation is only possible near chemical freeze-out Marcus Bleicher, Strange Quark Matter 2004

  27. Decay time analysis • In the model rho mesons are not re-created after T=120 MeV. Check with mass shift. Check hadronic vs leptonic Check centrality dependence • Deltas can be re-created until T=80-90 MeV.No centrality dependence of ratios Marcus Bleicher, Strange Quark Matter 2004

  28. Summary • K/ shows a peak around 20 GeV:- Peak can not be reproduced by transport models- Maybe sign of tri-critical point • Observed transverse flow is large:- Flow can not be described in standard transport models- Maybe sign of early QGP formation- Maybe sign of high mass resonances (low energies)- Maybe Cronin enhancement (high energies) • Resonances have been observed:- Apparently no resonance dissolution- Statistical models fail to describe data- Strong re-feeding and absorption effects Marcus Bleicher, Strange Quark Matter 2004

  29. Thanks • Elena Bratkovskaya • Henning Weber • Christina Markert • Patricia Fachini • Manuel Reiter • Sascha Vogel • Xianglei Zhu We do have a POST-DOC position! Marcus Bleicher, Strange Quark Matter 2004

More Related