2. March 27, 2003University of Buffalo Colloquium1 Status of the Search for the Quark-Gluon Plasma at RHIC Steven Manly Univ. of Rochester Colloquium at Univ. of Buffalo March 27, 2003 steven.manly@rochester.edu http://hertz.pas.rochester.edu/smanly/

3. March 27, 2003University of Buffalo Colloquium2 The starting point Yo! What’s da matter?

4. March 27, 2003University of Buffalo Colloquium3

5. March 27, 2003University of Buffalo Colloquium4

6. March 27, 2003University of Buffalo Colloquium5 What forces exist in nature? What is a force? How do forces change with energy or temperature? How has the universe evolved? How do they interact?

7. March 27, 2003University of Buffalo Colloquium6

8. March 27, 2003University of Buffalo Colloquium7 quarks leptons Gauge bosons u c t d s b e   W, Z, , g, G g Hadrons Baryons qqq qq mesons p = uud n = udd K = us or us  = ud or ud Strong interaction nuclei e atoms Electromagnetic interaction

9. March 27, 2003University of Buffalo Colloquium8 Quantum Chromodynamics - QCD Gauge field carries the charge q q distance energy density, temperature relative strength asymptotic freedom qq qq confinement q q

10. March 27, 2003University of Buffalo Colloquium9 Why do we believe QCD is a good description of the strong interaction? Deep inelastic scattering: There are quarks. From D.H. Perkins, Intro. to High Energy Physics

11. March 27, 2003University of Buffalo Colloquium10 Why do we believe QCD is a good description of the strong interaction? No direct observation of quarks: confinement

12. March 27, 2003University of Buffalo Colloquium11 Why do we believe QCD is a good description of the strong interaction? P. Burrows, SLAC-PUB7434, 1997 R. Marshall, Z. Phys. C43 (1989) 595 Need the “color” degree of freedom

13. March 27, 2003University of Buffalo Colloquium12 Why do we believe QCD is a good description of the strong interaction? Event shapes e + e -  Z o  qqe + e -  Z o  qqg

14. March 27, 2003University of Buffalo Colloquium13 Why do we believe QCD is a good description of the strong interaction? Measure the coupling P. Burrows, SLAC-PUB7434, 1997

15. March 27, 2003University of Buffalo Colloquium14 Strong interaction is part of our heritage

16. March 27, 2003University of Buffalo Colloquium15 Chiral symmetry: the “other” source of mass qq q QCD vacuum Quark condensate A naïve view …

17. March 27, 2003University of Buffalo Colloquium16

18. March 27, 2003University of Buffalo Colloquium17 Relativistic heavy ions Two concentric superconducting magnet rings, 3.8 km circum. A-A (up to Au), p-A, p-p collisions, eventual polarized protons Funded by U.S. Dept. of Energy $616 million Construction began Jan. 1991, first collisions June 2000 Annual operating cost $100 million Reached 10% of design luminosity in 2000 (1st physics run)!! AGS: fixed target, 4.8 GeV/nucleon pair SPS: fixed target, 17 GeV/nucleon pair RHIC: collider, 200 GeV/nucleon pair LHC: collider, 5.4 TeV/nucleon pair

19. March 27, 2003University of Buffalo Colloquium18 The view from above

20. March 27, 2003University of Buffalo Colloquium19 STAR

21. March 27, 2003University of Buffalo Colloquium20 Au-Au collision in the STAR detector

22. March 27, 2003University of Buffalo Colloquium21 Isometric of PHENIX Detector

23. March 27, 2003University of Buffalo Colloquium22 Brahms experiment From F.Videbœk

24. March 27, 2003University of Buffalo Colloquium23 The PHOBOS Detector (2001) Ring Counters Time of Flight Spectrometer 4  Multiplicity Array - Octagon, Vertex & Ring Counters Mid-rapidity Spectrometer TOF wall for high-momentum PID Triggering - Scintillator Paddles Counters - Zero Degree Calorimeter (ZDC) Vertex Octagon ZDC z y x   Paddle Trigger Counter Cerenkov 1m 137000 silicon pad readout channels

25. March 27, 2003University of Buffalo Colloquium24 Central Part of the Detector (not to scale) 0.5m

26. March 27, 2003University of Buffalo Colloquium25 Au-Au event in the PHOBOS detector

27. March 27, 2003University of Buffalo Colloquium26 The goals ã Establish/characterize the expected QCD deconfinement phase transition quarks+gluons hadrons ã Establish/characterize changes in the QCD vacuum at high energies: chiral symmetry restoration and/or disoriented chiral condensates ã Understand the nuclear equation of state at high energy density ã Polarized proton physics

28. March 27, 2003University of Buffalo Colloquium27 Beamline Terminology: angles

29. March 27, 2003University of Buffalo Colloquium28 Beamline Terminology: angles Pseudorapidity =  = Lorentz invariant angle with repect to the beampipe 0 +1 +2 +3 -2 -3

30. March 27, 2003University of Buffalo Colloquium29 Terminology: angles  = azimuthal angle about the beampipe Beamline

31. March 27, 2003University of Buffalo Colloquium30 “Spectators” Zero-degree Calorimeter “Spectators” Paddle Counter peripheral collisions central collisions N ch N part 6% Terminology: centrality Thanks to P. Steinberg for constructing much of this slide “Participants”

32. March 27, 2003University of Buffalo Colloquium31 Signatures/observables Energy density or number of participants Measured value Strange particle enhancement and particle yields Temperature J/  and  ’ production/suppression Vector meson masses and widths identical particle quantum correlations DCC - isospin fluctuations Flow of particles/energy (azimuthal asymmetries) jet quenching Each variable has different experimental systematics and model dependences on extraction and interpretation MUST CORRELATE VARIABLES

33. March 27, 2003University of Buffalo Colloquium32 RHIC operation 12 June, 2000: 1 st Collisions @  s = 56 AGeV 24 June, 2000: 1 st Collisions @  s = 130 AGeV July 2001: 1 st Collisions @  s = 200 AGeV Dec. 23, 2002: 1st d-Au collisions @  s = 200 AGeV Peak Au-Au luminosity = 5x10 26 cm -2 s -1 Design Au-Au luminosity = 2x10 26 cm -2 s -1 Ave luminosity for last week of ‘02 run = 0.4x10 26 cm -2 s -1 Run 1 Run 2 Run 3 Run 2:

34. March 27, 2003University of Buffalo Colloquium33 From Thomas Roser

35. March 27, 2003University of Buffalo Colloquium34 From Thomas Roser

36. March 27, 2003University of Buffalo Colloquium35 ã Energy flow, Particle multiplicity  high energy density ã Particle production  QCD is QCD is QCD ã Large flow, species yields  equilibration/thermalization ã Spectra, flow, jets  Jet quenching ã Not talking about Bose-Einstein correlations, strangeness enhancement, J/  suppression, balance function, direct photon production, mass shifts, width shifts, etc.

37. March 27, 2003University of Buffalo Colloquium36 Energy density of proton and lattice QCD calculations Expect deconfinement phase transition to occur at an energy density of 1-2 GeV/fm 3 Experimental results at RHIC imply  5 GeV/fm 3 4.6 GeV/fm 3 Assumes R=size of Au nucleus and T o =1fm/c PHENIX Collaboration, PRL 87 (2001) 052301

38. March 27, 2003University of Buffalo Colloquium37 PHOBOS Data on dN/d  in Au+Au vs Centrality and  s dN/d    19.6 GeV130 GeV 200 GeV Preliminary PHOBOS Typical systematic band (90%C.L.) Basic systematics of particle production

39. March 27, 2003University of Buffalo Colloquium38 Energy Dependence of Central dN/d  Scale by N part /2 & shift to  =  - y beam The “fragmentation region” extent grows with  s NN 19.6 GeV is preliminary19.6 GeV is preliminary Systematic errors not shown PHOBOS Au+Au dN ch /d  / dN ch /d  6% central Once you are smashed by a fast moving wall of bricks, it doesn’t make much difference if the bricks are going a little faster. That only determines how far your parts are spread along the path.

40. March 27, 2003University of Buffalo Colloquium39 (Mueller 1983) Universality of particle production From P.Steinberg

41. March 27, 2003University of Buffalo Colloquium40 pp/pp A+A e+e-e+e- From P.Steinberg Universality of particle production

42. March 27, 2003University of Buffalo Colloquium41 Universality e+e-e+e- Au+Au pp p+p  p+X : Universality of particle production From P.Steinberg

43. March 27, 2003University of Buffalo Colloquium42 Collision region is an extruded football/rugby ball shape Central Peripheral Elliptic flow

44. March 27, 2003University of Buffalo Colloquium43 Elliptic flow 12 6 3 9 12 3 6 9 12 Number of particles

45. March 27, 2003University of Buffalo Colloquium44 12 6 3 9 Number of Particles 12 3 6 9 12

46. March 27, 2003University of Buffalo Colloquium45 b (reaction plane) Elliptic flow dN/d(  R ) = N 0 (1 + 2V 1 cos (  R ) + 2V 2 cos (2(  R ) +... ) Determine to what extent is the initial state spatial/momentum anisotropy is mapped into the final state.

47. March 27, 2003University of Buffalo Colloquium46 Elliptic Flow at 130 GeV (PHOBOS : Normalized Paddle Signal) Hydrodynamic limit STAR: PRL86 (2001) 402 PHOBOS preliminary Hydrodynamic limit STAR: PRL86 (2001) 402 PHOBOS preliminary Thanks to M. Kaneta

48. March 27, 2003University of Buffalo Colloquium47 Flow vs P t and  Hydro describes low pt vs. particle mass, fails at high p t and high-  T. Hirano (consider velocity and early, self- quenching asymmetry)

49. March 27, 2003University of Buffalo Colloquium48 Chemical equilibration and freezeout temperature M. Kaneta, STAR Collaboration Thermal models can describe data VERY well. Thermal model lets us put data on QCD phase diagram –RHIC energies appear close to T c LEP F. Becattini, hep-ph/9701275

50. March 27, 2003University of Buffalo Colloquium49 Spectra 0.2<y   <1.4 The fun starts when one compares this to pp spectra STAR results, shown at QM02

51. March 27, 2003University of Buffalo Colloquium50 –Production of high p T particles dominated by hard scattering –High p T yield prop. to N coll (binary collision scaling) –Compare to pp spectra scaled up by N coll –Violation of N coll scaling observed at 130GeV (PHENIX/STAR) –Jet quenching? Comparing Au+Au and pp Spectra _ _ Au+Au

52. March 27, 2003University of Buffalo Colloquium51 Suppression in Hadron Spectra Shown by T. Peltzmann at QM02

53. March 27, 2003University of Buffalo Colloquium52 Jet-quenching: hard parton interacts with medium, which softens the momentum spectrum in A-A relative to pp

54. March 27, 2003University of Buffalo Colloquium53 Peripheral Au+Au data vs. pp+flow STAR, David Hartke - shown at QM02 Count tracks around very high p T particle

55. March 27, 2003University of Buffalo Colloquium54 Central Au+Au data vs. pp+flow STAR, David Hartke - shown at QM02 Away side jet disappears!!

56. March 27, 2003University of Buffalo Colloquium55 Jet-quenching also gives break in flow vs. p T

57. March 27, 2003University of Buffalo Colloquium56 Initial state vs. final state effects Jet-quenching is a final state effect - “Weisaker- Williams” color field of parton interacting with colored medium. Energy loss is medium-size dependent (radiated wavelengths less than source size) Initial state effect - saturation models color glass condensate ( recent review: Iancu, Leonidov, McLerran, hep-ph/0202270 ) can also qualitatively explain some features of the data Current d-Au run will help untangle this mess!

58. March 27, 2003University of Buffalo Colloquium57 Showed you too much - I apologize Showed you too little - I apologize Status of the search for the QGP at RHIC? RHIC/experiments running very well Up till now … characterization and model tuning

59. March 27, 2003University of Buffalo Colloquium58 ã Hot, dense, opaque medium is formed ã Energy density above lattice predictions for deconfined state ã Local thermal equilibrium achieved ã Full 3-d structure away from mid-rapidity not yet understood ã Interesting signals being pursued … jet-quenching? Probably standing on the precipice of a claim/discovery Remains to be seen if systematic study and pursuit of the surprises leads to anything beyond the duck! Future = statistics (J/  + more), vary species/energies, LHC Is it a duck?

60. March 27, 2003University of Buffalo Colloquium59

61. March 27, 2003University of Buffalo Colloquium60