1 / 20

Bulk properties at RHIC

Bulk properties at RHIC. Motivation Freeze-out properties at RHIC STAR perspective STAR PHENIX, PHOBOS Time-span estimates Summary and Open Questions. Olga Barannikova (Purdue University). Motivation. Bulk properties – “Soft Physics” Spectral shapes:

ppotter
Download Presentation

Bulk properties at RHIC

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. Bulk properties at RHIC • Motivation • Freeze-out properties at RHIC • STAR perspective • STAR PHENIX, PHOBOS • Time-span estimates • Summary and Open Questions Olga Barannikova (Purdue University)

  2. Motivation Bulk properties – “Soft Physics” Spectral shapes: kinetic freeze-out properties transverse radial flow Tkin @ kinetic freeze-out X,W,f different behavior? Flavor composition: chemical freeze-out properties Tch@chemical freeze-out strangeness production strangeness enhancement? Resonance production: regeneration and rescattering K*, L(1520), f Partonic collectivity Thermalization Time span Berkeley School, May 2005

  3. X+ Particle Identification dE/dx method K+ K_ Topological method K* K0s  +    p + p X  L + p K(892)  + K  (1020)  K + K (1520)  p + K Berkeley School, May 2005

  4. Transverse mass spectra K L K0s W • f K* X STAR Preliminary Variety of hadron species: K , K0s, K*, , , ,, (1520), S(1385), X(1530),  , p, D++ pp, Au+Au, d+Au Same experimental setup! Berkeley School, May 2005

  5. Statistical Model Fit 200 GeV Au+Au Stable particle ratios well described with Tch = 16010 MeV, mB = 24 5 MeV Thermalization ? Berkeley School, May 2005

  6. Chemical Freeze-out Properties 200 GeV Au+Au Close to net-baryon free p,K,p Close to chemical equilibrium ! p,K,p,L,X Berkeley School, May 2005

  7. where and Tdec = 100 MeV Spectral shapes Blast-wave model: E.Schnedermann et al, PRC48 (1993) 2462. , K, p  T= 90MeV, b=0.6 X,   T=160MeV, b=0.45 Common hydro description ? Kolb and Rapp, PRC 67 (2003) 044903. Sudden Single Freeze-out ? A. Baran et al.; nucl-th/0305075. Berkeley School, May 2005

  8. , K, p  T= 90MeV, b=0.6c T=160MeV  , K, p  b=0.5 c p- p- K- K- Fit details Berkeley School, May 2005

  9. p- p,GeV/c p,GeV/c K- p,GeV/c Resonance effects? Thermal model: • One freeze-out Tchem = Tkin = T • Complete treatment of hadronic states • Boost-invariance at mid rapidity • T, B - fixed by ratios, ,  - fixed by p- spectra • W. Broniowski, et al, nucl-th/0305075 Berkeley School, May 2005

  10. /dof  2 BW fit with Resonances /dof  6 • More complete study of resonance effects: code from • U.A.Wiedemann, U.Heinz, PRC 56 (1997), 3265 /dof  2 Berkeley School, May 2005

  11. p- K- p- K- • PHENIX • STAR • PHOBOS p p Other RICH experiments? • STAR only • PHENIX+PHOBOS+STAR  T= 96 MeV, b=0.57 c • Consistent BW results Berkeley School, May 2005

  12. Kinetic Freeze-out Kinetic FO temperature • Sudden Single Freeze-out ?* Radial flow velocity • p,K,p: Tkindecreases with centrality • X: Tkin = const • , X and W flow Berkeley School, May 2005

  13. Tc Partonic flow? Tkin ~ Tch ~ 160 MeV  ~ 0.45 rescattering Tkin ~ 90 MeV,  ~ 0.6 Freeze-out Evolution Lattice QCD: Tc = 17010 MeV • Chemical FO close to hadronization • Strong flow at hadronization Berkeley School, May 2005

  14. Time Scale Tch Tkin For massless particles in equilibrium: Entropy density ~ T3 Berkeley School, May 2005

  15. Hadrongas Chemical FO Kinetic FO Dense medium Hadronization Chemical FO Kinetic FO  K*  K K* measured lost  K K*   K* K measured K K Resonance Production and Survival • pp • No extended initial medium • Chemical freeze-out • Kinetic freeze-out close to the Chemical freeze-out pp • Au+Au • Extended hot and dense phase • Thermalization & Chemical freeze-out • Kinetic and Chemical freeze-outs are separated Tch Yields Tkin Spectra time • Resonances: • Two competing effects: regeneration and rescattering can change yields after chemical freeze-out • Ratio to stable particle reveals information time-span between Chemical and Kinetic FO time Au+Au Berkeley School, May 2005

  16. <pT> in Au+Au at 200 GeV Signal loss at low pT: UrQMD: signal loss at low pT due to rescattering of decay daughters  <pT> is higher UrQMD has long lifetime (Dt 5-20fm/c)  ++ K* Signal loss of ~70% for K* <pT> increase from pp to Au+Au: K(892) <pT> (GeV/c) Proton <pT> (GeV/c) Centrality 0% - 10% 1.080  0.120 1.090  0.110 50% - 80% 1.030  0.120 0.760  0.050 pp 0.680  0.040 0.620 0.040 Berkeley School, May 2005

  17. Resonances and Stat. Model Resonance Suppression Strangeness Enhancement 200 GeV pp 200 GeV Au+Au • In pp particle ratios are well described • In Au+Au only stable particle ratios are well described Berkeley School, May 2005

  18. Ratios M. Bleicher et al. J. Phys. G 25 (1999) 1859 Thermal model σ(Kπ) σ(ππ) • UrQMD • Marcus Bleicher and Jörg Aichelin • Phys. Lett. B530 (2002) 81. M. Bleicher and Horst Stöcker .Phys.G30 (2004) 111. Life time [fm/c] :  = 40 L = 13 K* = 4 ++ = 1.7 K*  + K   K + K   p + K ++  p+ p Resonance ratios modified from pp to Au+Au Rescattering and regeneration is needed !  > 4 fm/c (lower limit) Berkeley School, May 2005 Rescattering and regeneration is needed !

  19. Summary • Chemical Freeze-out conditions: • Particle ratios suggest equilibrium • Invariant Tch ~160 MeV ~ TC -near lattice phase boundary • Thermal model does not reproduce resonances • Kinetic freeze-out conditions: • p,K,p vary with centrality : Tkin,b • Collectivity (strong flow) builds up very early • Multistrange baryons:Tkin ~ Tch • Between freeze-outs: • Chemical  kinetic: Dt ~6fm/c • Resonances are strongly affected by rescattering • Dt >4 fm/c rescattering-based estimate – in agreement with blast wave results Berkeley School, May 2005

  20. Soft Hard Intermediate • T = 90 MeV • T = 160 MeV • T = 90 MeV • T = 160 MeV STAR Preliminary 0 2-3 GeV/c 6-7 GeV/c pT p- T = 87 MeV Hydro,Statistical Model pQCD, Fragmentation Jet quenching T = 101 MeV p- K- ?? T = 109 MeV • PHENIX • STAR • PHOBOS p p p Open Questions and a Wish List Applicability limits? Theoretical models for extended momentum range Berkeley School, May 2005

More Related