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Global Observables Particle Spectra and Yields

Global Observables Particle Spectra and Yields. Quark Matter 2002, Nantes July 18-24, 2002. “ I don’t want to have your job ….” Encouraging remark by Jörg Aichelin two days before this talk. Thomas Ullrich. 99.5%. Understanding “Bulk” Matter. Studying Matter:

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Global Observables Particle Spectra and Yields

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  1. Global ObservablesParticle Spectra and Yields Quark Matter 2002, Nantes July 18-24, 2002 “I don’t want to have your job ….” Encouraging remark by Jörg Aichelin two days before this talk Thomas Ullrich

  2. 99.5% Understanding “Bulk” Matter Studying Matter: • Global Observables Nch, ET, pT  e, S, … • Particle Yields & Ratios  Tch, mB, mS, … • Particle Spectra  Tfo, flow, stopping, … • Correlations (see Sergei and Scott) • … and all that in pp, pA, AA STAR preliminary

  3. Plenary Talks: M. Baker (Phobos) A+A @RHIC H.G. Fischer (NA49) p(n)+p, p+A, p+(p)A @SPS G. VanBuren (STAR) A+A @RHIC V. Manzari (NA57) A+A @SPS T. Chujo (PHENIX) A+A @RHIC V. Leeuven (NA49) A+A @SPS L. Bearden (BRAHMS) A+A @RHIC … and many, many posters Parallel Talks: Mischke (NA49) Wang (STAR) Fachini (STAR) Yamamoto (STAR) Suire (STAR) Hoehne (NA49) Oeurdane (BRAHMS) Lee (BRAHMS) Bazilevsky (PHENIX) Steinberg (PHOBOS) Mukhopadhyay (PHENIX) Burward-Hoy (PHENIX) Kreps (NA49) Wosiek (PHOBOS) Elia (NA57) Castillo (STAR) Related Talks at QM 2002

  4. PHENIX & STAR preliminary RHIC: Nch at mid-rapidity A. Bazilevsky (PHENIX) • Consistency of RHIC results • PHENIX: PC, STAR: TPC • PHOBOS: Si BRAHMS: Si & Scint. Ratio R(200/130): BRAHMS: 1.14  0.05 PHENIX: 1.17  0.03 PHOBOS: 1.14  0.05 STAR: 1.19  (no sys. yet)

  5. Nch(sNN) – Fresh Look from a Different Perspective • P. Steinberg (PHOBOS) Particle density near midrapidity _ e+e-& AA pp & pp (dN/dyT ) e+e- scales like AA near mid-rapidity

  6. P. Steinberg (PHOBOS) Universality Leading Particle Effect Nch (ISR pp) Basile et al (1980-84) Subtract energy of leading protons to define effective energy

  7. Nch(sNN) – Universality of Total Multiplicity? Total charged particle multiplicity / participant pair Same for all systems at same s(seff for pp) • pQCD e+e- Calculation (A. Mueller, 1983) Accidental, trivial?Is plain parton fragmentation all there is in AA above s ~ 20 GeV?

  8. _ pp Nch: Centrality Dependence at RHIC (SPS) PHOBOS Au+Au |h|<1 M. Baker (PHOBOS) 200 GeV 130 GeV Au+Au 19.6 GeV preliminary (preliminary) • Everything counts: • Nch|h=0 described nicely by KN (hard + soft) • Nch scales with Npart

  9. ET/ Nch from SPS to RHIC A. Bazilevsky (PHENIX) PHENIX preliminary PHENIX preliminary Independent of centrality Independent of energy Surprising fact: SPS  RHIC: increased flow, all particles higher pT still ET/ Nch changes very little Does different composition (chemistry) account for that?

  10. pT of Charged Hadrons from SPS to RHIC G. VanBuren & Poster by M. Calderon (STAR) increase only ~2% STAR preliminary Saturation model: J. Schaffner-Bielich, et al. nucl-th/0108048 D. Kharzeev, et al. hep-ph/0111315 Many models predict similar scaling (incl. hydro) Need data around s = 70 GeV to verify (or falsify)

  11. Ratios, Ratios, Ratios …. • Huge amount of results from all 4 RHIC experiments: • systematic studies of: p-/p+, K-/K+,p/p,/ ,/,/, p/p, K/p , /, /h, , /p, f/K, K*/K, … • many as function of pT, Npart • at s of (20), 130, and 200 GeV • with and without feed-down correction () • BRAHMS  large y coverage and reach to high pT • PHENIX  reach to high pT • STAR multi-strange baryons (many ratios already discussed by P. Peitzmann and D. Röhrich)

  12. Identical Particle Ratios at RHIC @ 200 GeV All experiments: p-/p+ 1 K-/K+ 0.95 Tatsuya Chujo (PHENIX) • Flat in pT • No centrality dependence

  13. p/p at RHIC @ 200 GeV central peripheral Tatsuya Chujo G. Kunde (STAR) Discrepancy between PHENIX and STAR for central collisions but clear picture overall: STAR preliminary central PHOBOS 0.74 ±0.02(stat)± 0.03(sys) BRAHMS: 0.75 ±0.04 PHENIX: 0.70  0.04 (stat)  0.1(sys)

  14. NEW: Rapidity dependence of ratios at RHIC I. Bearden (BRAHMS) BRAHMS 200 GeV At mid-rapidity: Net-protons: dN/dy  7 proton yield: dN/dy  29  ¾ of all protons from pair-production

  15. K-/K+ and p/p from AGS to RHIC I. Bearden (BRAHMS) Becattini caluclation using statistical model: T=170, gs=1 (weak dependency) vary mB/T  K+/K- andp/p K- /K+=(p/p)1/4 is a empirical fit to the data points K-/K+ driven by ms ~ exp(2ms/T) p/p driven by mB ~ exp(-2mB/T) ms = ms (mB) since <S> = 0 BUT: Holds for y  0 (BRAHMS y=3)

  16. p/p Tatsuya Chujo (PHENIX) p/p Central Peripheral • Proton yield is comparable with pions @ 2 GeV in central collisions, less in peripheral

  17. First Identified Particle Ratios in pp @ 200 GeV Poster by S. Sato (PHENIX) not feed-down corrected PYTHIA p/p  0.83  0.6  1 N.B.: Nexus 3.0 includes new string model (parton based Gribov-Regge theory) to overcome the failure of present string models to describe/ < 1 in pp (e.g. NA49 160 GeV) Always/  1 in string models Nexus 3.0 predicts preliminary PHENIX results accurately  0.8

  18. Statistical Model: What Drives the Fit? D. Magestro (Poster and JP G28 2002 1745)

  19. Statistical Model: First Look at AuAu @ 200 GeV • All 200 GeV data taken from QM talks: • F. Wang (STAR)/G. Van Buren (STAR)/ • T. Chujo (PHENIX)/Ouerdane (BRAHMS) • J. Lee (BRAHMS)/B. Wosiek (PHOBOS) • New 130 GeV data are: • C. Suire (STAR)/J. Castillo (STAR) Predictions: phenomenologically: mB ~ 1.3 GeV (1+s/4.5 GeV)-1 assume unified freeze-out condition: E/N ~ 1.1 GeV  T

  20. Centrality Systematics of Chemistry G. VanBuren and M. Kaneta (STAR) • Statistical model using STAR • data at 130 GeV at different centralities • Fits without (red) and with (blue)X • mq (mB) increasing with centrality • ms close to zero • gs increasing with centrality

  21. Statistical Models: from AGS to RHIC M. van Leeuwen (NA49) Different implementation of statistical model (Kaneta/Nu, Beccatini, PBM et al., …) Fact: all work well at AGS, SPS and RHIC Slight variations in the models, but roughly: Does the success of the model tells us we are dealing indeed with locally chemically equilibrated systems? this+flow  If you ask me YES! Fit by Beccatini using total yields from NA49 hadron gas fit with partial strangeness saturation

  22. Rapidity Spectra: Boost-Invariance at RHIC ? M. Baker (PHOBOS) D. Ouerdane (BRAHMS)

  23. Boost-Invariance at RHIC ? p- p- • dN/dy of pions looks boost-invariant BUT • change in slopes for rapidity already from 0  1 • BRAHMS (J.H. Lee): no change in proton slope from y = 0  3 BUT increase in dN/dy •  Boost invariance only achieved in small region |y|<0.5

  24. Identified Particle Spectra at RHIC @ 200 GeV BRAHMS: 10% central PHOBOS: 10% PHENIX: 5% STAR: 5% Compiled with the help of F. Laue

  25. Identified Particle Spectra at RHIC @ 200 GeV Feed-down matters !!!

  26. Interpreting the Spectra • The shape of the various particle spectra teach us about: • Kinetic freeze-out temperatures • Transverse flow • The stronger the flow the less appropriate are simple exponential fits: • Hydrodynamic models (a la Heinz/Kolb/Shuryak/Huovinen/Teaney) • Hydro inspired parameterizations (Blastwave) • Blastwave parameterization: • Ref. : E.Schnedermann et al, PRC48 (1993) 2462 (modifications by Snellings, Voloshin) • Very successful in recent month • Spectra • HBT (incl. the Rout/Rside puzzle) • Flow spectra (p) HBT See also talk by J. Burward-Hoy (PHENIX) b

  27. Blastwave Fits at 130 & 200 GeV Results depend slightly on pT coverage STAR: Tfo ~ 100 MeV bT ~ 0.55c (130) & 0.6c (200) PHENIX: Tfo ~ 110 MeV (200) bT ~ 0.5c (200) 200 GeV Fits see poster M. Kaneta (STAR)

  28. What flows and when? M. Kaneta/N. Xu (STAR) <pT> prediction with Tth and <b> obtained from blastwave fit (green line) STAR <pT> prediction for Tch = 170 MeV and <b>=0 pp no rescattering, no flow no thermal equilibrium preliminary F. Wang  and  appear to deviate from common thermal freeze-out Smaller elast? Early decoupling from expanding hadronic medium? Less flow? What’s about partonic flow?

  29. Mid-Rapidity mT spectra in 158 AGeV (SPS) M. van Leeuwen (NA49)

  30. Does it flow? Fits to Omega mT spectra M. van Leeuwen (NA49) C. Suire (STAR) STAR preliminary RHIC SPS/NA49 bT is not well constrained ! • What do we now about elast of  and  ? • May be it flows, and may be they freeze out with the others • Maybe  and  are consistent with a blastwave fit at RHIC • Need to constrain further  more data & much more for v2 of 

  31. Other Attempts: The Single Freeze-Out Model • Single freeze-out model (Tch=Tfo) • (W. Broniowski et. al) fit the data • well. •  Thermal fits to spectra are not enough to make the point. • To discriminate between different models they have to prove their validity by describing: • Spectra (shape & yield) • Correlations (HBT, balance function, etc.) • Flow • Only then we can learn … Compilation and comparison by B. Hippolyte

  32. Model Crisis • “Better ask me which models we can’t kill…” I. Bearden • Flood of data from SPS & RHIC • new probes • correlations between probes • higher statistics & precision • Models (Generators) are behind • The majority of models in RHI fails already describing global observables (possible exception AMPT) • Many models describe “A” well but fail badly at “B”  can still be useful but limited scope New efforts badly needed !

  33. pp Au+Au 40% to 80% STAR Preliminary STAR Preliminary 0 f0K0S  K*0 0 f0 K0S  K*0 0.2  pT  0.8 GeV/c 0.2  pT  0.9 GeV/c Things to Look Forward to (I) This QM: First glance at resonances at RHIC: 0(770)  + - and f0(980)  + - |y| < 0.5 P. Fachini (STAR) • Short-lived resonances: • provide information on the collision dynamics • rescattering  regeneration

  34. Things to Look Forward to (II) ϕ Production via ϕ K+K- andϕ e+e- Eugene Yamamoto (STAR) D. Mukhopadhyay (PHENIX)   e+e- Mass Spectrum Fitted Mass = 1019 MeV/c2 Fitted  = 7.1  3 MeV/c2 PHENIX preliminary PRELIMINARY AuAu @ 200 GeV STAR mass [GeV/c2] • only probe at RHIC for chiral symmetry restoration (until PHENIX upgrade) • STAR & PHENIX can (in principle) measure both channels • requires high statistics, high precision measurement  K+K- PHENIX preliminary mass [GeV/c2]

  35. Instead of the Summary of the Summary • A Wish for Next QM ;-) • Let this be the last QM summary session on: • Spectra • Strangeness • Flow • HBT • We learn more by combing the various pieces and putting them into context • Thermalization, Chemical and Kinetic Freeze-out Conditions, and System Dynamics can only be studied (and are studied) using all the pieces together

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