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Experimental Summary

Experimental Summary. John Harris Yale University. Outline. Baryon Density Particle Production Strangeness Enhancement Statistical Models and Chemical Freezeout Spectra and Thermal Freezeout Spectral components Thermal Flow Blast Wave HBT Resonances and Timescales

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Experimental Summary

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  1. Experimental Summary John Harris Yale University

  2. Outline • Baryon Density • Particle Production • Strangeness Enhancement • Statistical Models and Chemical Freezeout • Spectra and Thermal Freezeout • Spectral components • Thermal • Flow • Blast Wave • HBT • Resonances and Timescales • High transverse momentum components • Charm Production • Open Charm • J/y • Interpretations • Puzzles still to solve. What’s still to learn? • Note - Results from this Conference are not only on strangeness…. • Comprehensive picture required for understanding

  3. HUGE Advances in Experimental Program

  4. 20 AGeV : not yet analysed The NA49 Energy Scan Program V. Fries (NA49) SQM03 Central Pb+Pb Data Analysis of Single Particle Spectra & Yields : • : Phys. Lett. B491 (2000) 59 • : Phys. Lett. B538 (2002) 275 K, : Phys. Rev. C66 (2002) 054902

  5. preliminary preliminary H. Caines (STAR) SQM03 STAR Strange Spectra @ 200 GeV X STAR Preliminary K0s STAR Preliminary f STAR Preliminary K* L STAR Preliminary W Preliminary K

  6. Anti-Baryon to Baryon Ratios Baryon density? String fragmentation? Coalescence?

  7. Au+Au STAR p+p √s = 200 GeV prelim. SPS sNN = 17.4 GeV • at RHIC - not baryon-free! • Pair production > baryon transport: • 80% of protons from pair production • 20% from initial baryon number • (transported over 5 units of rapidity!) • Baryon transport dynamics? Billmeier (STAR) SQM03 Anti-Baryon/Baryon Ratios • Baryon-pair production increases with s • Mid-rapidity region near B/B = 1 at RHIC •  low net baryon density • Ratios fit into Quark Coalescence Model • or Statistical Model! • Data for |y| < 0.5 only: • i.e. not global  local equilibrium?

  8. Separating Strangeness Enhancementand Baryon Density

  9. Lines of constant lS I. Increase instrange/non-strangeparticle ratios PBM et al., hep-ph/0106066 total II. Maximum isreached mesons III. Ratios decrease (Strange baryonsaffected more stronglythan strange mesons) baryons hidden strangeness mesons <E>/<N> = 1 GeV Peaks at 30 A GeV in AA collisions due to strong mB dependence R. Bellwied SQM03 Wroblewski factor evolution dependent on T and mB dominated by Kaons Wroblewski factor

  10. K+/ K- STAR preliminary NA49 & STAR K-/p- K+/p+ K/p K-/p- STAR L/p NA49 Preliminary NA49 & STAR L/p Pair production increases with s Net baryons peak at low s Strange / light Quark Ratios - K/p, L/p vs s

  11. Indication for kink structure also for K-/- ? Sharp maximum for K+/+ ! V. Fries (NA49) SQM03 Energy Dependence : Total K/ Ratios

  12. where  not published : Energy Dependence: Strangeness to Entropy? V. Fries (NA49) SQM03 Data at 30 AGeV support phase transition scenario (Statistical Model of Early Stage)

  13. Strangeness Enhancement at SPS L. Sandor (NA57) SQM03 Factor 20 enhancement for W in AA relative to pp and pA

  14. hep-ph/0211159 “Npart > 60 Grand Canonical ok to <10%” - Stachel Strangeness Enhancement at SPS

  15. Strangeness Enhancement at RHIC equilibration volume ? STAR Preliminary Tounsi et al.

  16. Strangeness Enhancement as Function of Energy NA49 preliminary Anti-strange baryon production is a measure of enhancement, whereas strange baryon production at RHIC is strongly affected by vanishing net baryon density

  17. f Data J. Ma (STAR) SQM03 STAR preliminary • |y|<0.5 • Exponential function fit well to the spectra of AuAu collisions • Spectra from pp collisions fit well to a power law function Fit functions: AuAu: mt exponential pp: pt power law

  18. Energy Dependence f Production STAR preliminary STAR preliminary (central) AGS SPS RHIC J. Ma (STAR) SQM03

  19. Strange Particle Ratios, Yields and the Statistical Model Chemical Equilibration?

  20. Statistical Model Fits at AGS & SPS J. Stachel SQM03

  21. Particle Yields at 40 and 80 AGeV V. Fries (NA49) SQM03 Statistical Model fits courtesy of F. Beccatini Particle yields at all three energies can be fitted by the Hadron Gas Model with partial strangeness saturation

  22. Statistical Model Fits at RHIC H. Caines (STAR) SQM03 What about the resonances?!? As we know beautiful agreement between models and data

  23. Phase Diagram of Nuclear Matter J. Stachel and other versions SQM03

  24. Resonances Medium modifications? Timescales of reaction: chemical – thermal freezeout?

  25. K p L* c = 13 fm c = 44 fm f K* K K K p c = 4fm Short-lived Resonance Production • Resonances formed at Chemical Freeze-out • Extract yield, spectra, mass, width of various resonances • Survival time between Chemical and Kinetic Freeze-outs • Resonances sensitive to Time Scale & Dynamics of System

  26. Short-lived Resonances r (770)fo(980)K*(892)f (1020)S(1385)(1520) Width  : 149 MeV 57.1 MeV 50.7 MeV 4.4 MeV 36-39 MeV15.6 MeV Lifetime  : 1.3 fm/c 2.6 fm/c 3.9 fm/c 44 fm/c 5.2 fm/c12.8 fm/c Decay mode: pp (~100%)pp (~67%)Kp (~100%)K+K-(49%) Lp (88%) pK (~22%) • Useful when resonance lifetimes span the range of fireball lifetimes. • f(1020) long lifetime (44 fm/c) • S(1385) and K*(892) have 2 - 3 times shorter lifetimes than (1520). • r(770) and fo(980) even shorter

  27. K* Daughter particles’ Rescattering Effect destroys part of signal K* lost  K K*   K* Regeneration Effect compensates K K K K* measured Ratio to stable particle reveals timing between chemical & thermal freeze-out Resonances and Survival Probability H. Caines, H. Zhang, …. (STAR) SQM03 Initial yield established at chemical freeze-out stage  K* K K* measured Thermal freeze-out Chemical freeze-out time Haibin Zhang, SQM 2003 3

  28. Summary of Resonance Ratios H. Caines (STAR) SQM03 STAR Preliminary Au-Au and p-p √s=200GeV L(1520) ->pK (13 fm/c) K* -> Kp ( 4 fm/c) r -> pp (1.3 fm/c) UrQMD:signal loss K*(892) (1520) SPS (17 GeV) [1] 66% 50% RHIC (200GeV) [2] 55% 30% P. Fachini, L. Gaudichet, H. Zhang

  29. * (1520) /  ratio L. Gaudichet (STAR) SQM03 P.Braun-Munzinger et al, PLB 518 (2001) 41 D. Magestro, private communication     STAR Central point • AuAu min-bias data and central point are consistent. • Suppression of observed lambda*, already in peripheral event • Show the same trend as the K* (Haibin Zhang, Sun)

  30. π+π- Raw Invariant Mass Distribution from Data Au+Au 40% to 80% Minimum Bias pp sNN = 200 GeV ρ0 f0 K0S ωK*0f2 ρ0 f0K0S ωK*0 STAR Preliminary STAR Preliminary counts/(10 MeV/c2) 1.2 pT 1.4 GeV/c |y|  0.5 0.8 pT 0.9 GeV/c |y|  0.5 Statistical error only Statistical error only • 1.2106 peripheral Au+Au events and 1.1107 minimum bias pp events • Follow previous e+e- and pp measurements that do not extract l = 1 ρ0 production • Relativistic Breit-Wigner  Phase Space fixed width ρ0Г = 160 MeV and f0Г = 75 MeV nominal width + detector resolution • f0massfixed  M ~ 980 MeV/c2 P. Fachini (STAR) SQM03

  31. ρ0Mass STAR Preliminary |y|  0.5 BW  PS BW STAR Preliminary |y|  0.5 Statistical errors only Statistical errors only ρ0mass measured in pp at s = 27.5 GeV (pT 0 and xF  0) M. Aguilar-Benitez et.al., Z. Phys. C50, 405 (1991) • pp at s = 27.5 GeV  M= 762.6  2.6 MeV/c2 • PDG average hadroproduced ρ0 M= 769.0  0.9 MeV/c2 • PDG average e+e-ρ M= 775.9  0.5 MeV/c2 • ρ0 mass pt dependent and systematically lower than previous pp measurement in both minimum bias pp and peripheral Au+Au collisions P. Fachini (STAR) SQM03

  32. STAR Preliminary K*0 Mass and Width Distribution H. Zhang (STAR) SQM03 K*0 Mass shift in p+p and Au+Au at low pT possible in-medium dynamic effect modified K*0 mass and the line shape K*0 width matches the MC prediction 8

  33. = ss : more sensitive to strangeness • enhancement than kaons ? n.b. : small deviation from PDG mass seen at all three Pb+Pb data sets, but not in pp.  at 40 and 80 AGeV V. Fries (NA49) SQM03

  34. Spectra Thermal Freezeout Transverse (radial) flow? pQCD hard processes? Flavor-dependent jet-quenching?

  35. <pt> and p + p collisions R. Witt (STAR) SQM03 K0s Not flow in p-p ……. so evidence for mini-jets?

  36. Slope T from fit to mT spectra: Transverse Flow STAR preliminary

  37. K*0 <pT> in Au+Au collisions is larger than in p+p collisions K*0 <pT> in peripheral Au+Au collisions is larger than anti- proton <pT>  Rescattering? K*0 <pT> in central Au+Au collisions is comparable toanti- proton <pT>  Rescattering + Regeneration? K*0 <pT> in Au+Au collisions is “flat” vs. number of charged particles STAR Preliminary K*0 <pT> vs. Centrality H. Zhang (STAR) SQM03 11

  38. <pT> centrality dependence J. Ma (STAR) SQM03 1)p, K, p mean transverse momentum <pT> increase in more central collisions; 2) Heavier mass particle <pT> increase faster than lighter ones as expected from hydro type collective flow; 1)p, K, p mean transverse momentum <pT> increase in more central collisions; 2) Heavier mass particle <pT> increase faster than lighter ones as expected from hydro type collective flow; 3)f-meson seems to flow differently. Star preliminary

  39. Energy Dependence : Kaon Slope Parameters V. Fries (NA49) SQM03 No dependence of kaon slope parameters on energy at SPS Modification of EOS in phase transition region ? see hep-ph/0303041

  40. strong mass dependence of pT spectra. L/K- , f/K- ratios increase as pt increases! Ratio  1 at high pt Indicates flow (+ rescattering) rather than novel baryon dynamics at high pt? Strange Baryons and Strange Mesons as pT Increases

  41. 158 AGeV pions and deuterons not included in fit Kinetic Freeze-Out : mid-rapidity mt spectra V. Fries (NA49) SQM03 radial flow fit (blast wave) also describes heavy hyperons common freeze-out behaviour for all measured particles

  42. 40 AGeV Kinetic Freeze-Out at 40 AGeV V. Fries (NA49) SQM03 good description also at 40 AGeV and 80 AGeV (not shown) Parameters T and T similar for all three energies

  43. • , (?): Show different thermal freeze-out behaviour:  ,K,P, ,K,P, PHENIX/STAR Kinetic freeze-out at 130 GeV J. Castillo (STAR) SQM03 • , K, P, : Common thermal freeze-out at T~100MeV and <>~0.52c Assume br= bs(r/R) Tfo - (), 1 and 2  contours • Early freeze-out due to smaller cross-section ? • Radial flow developing at early times? STAR Preliminary

  44. f, X, W, kinetic freeze outBlast wave fit @ 130 GeV F. Retiere SQM03 Plain: T = 155 MeV, rmax = 0.72 Dash: T = 108 MeV, rmax = 0.88 p, K, p from PHENIX L From STAR K* rmax f X f, X, W From STAR W X W, and X spectra: preliminary STAR data K* spectra: Phys. Rev. C66, 061901(R) (2002) f spectra: Phys. Rev. C 65, 041901(R) (2002)

  45. Small yield of L(1520) and K* L(1520) and K* produced at “lower temperature” than other hadrons? Destroyed during time from chemical to thermal freeze out Consistency checkHints of non-zero emission duration F. Retiere SQM03 STAR preliminary data K*/K L(1520)/L Thermal calculations from D.Magestro PLB 518 (2001) 41 Chemical freeze out parameters: T = 176 MeV, mB = 41 MeV STAR data K* (Haibin Zhang) L(1520)(L. Gaudichet, C. Markert)

  46. HBT vs mt S. Bekele (STAR) SQM03 ? Wiedemann and Heinz expect: to drop with 1/mat due to collective flow. (a ~ 0.5) Rinv for K0s does not seem to obey same mt scaling Need more detailed studies before conclusive statement made

  47. Kaons 200 GeV Au-Au STAR Preliminary Observing Hadronization Timescale G. Westfall (STAR) SQM03 The Premise: • Charge/anti-charge pairs are created close in space-time • Early creation (hadron gas) • Longitudinal expansion and rescattering pulls pairs apart • Loose correlation in rapidity • Late creation (after deconfined phase?) • Pairs only form at hadronization, late in collision • Less rescattering • Less loss of correlation in rapidity • Balance function tries to measure this correlation • Width of balance function then related to time between hadronization and freeze-out

  48. STAR Preliminary Balance Function at 200 GeV G. Westfall (STAR) SQM03 Smooth transition from p-p to Au-Au K narrower than p Narrower widths for more central data: Delayed hadronization?

  49. High Transverse Momentum

  50. The PHENIX approach:Leading Photon Correlations 0 incoming partons associated h trigger  J. Velkovska SQM03 • Select events with a photon of pt > 2.5 GeV/c. Mostly ’s from decay of a high pt  (leading particle) • Build distributions in delta  -space of the charged hadrons relative to the trigger photons. pp AuAu PHENIX Preliminary 2-4 GeV • black = pair distribution • green = mixed event pair distribution • purple = bkg subtracted distribution In AuAu: add v2 component

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