Exploring Quark-Gluon Plasma at RHIC: A Fascinating Journey into Particle Physics

1. 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/ University of Buffalo Colloquium

2. The starting point Yo! What’s da matter? University of Buffalo Colloquium

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5. What forces exist in nature? What is a force? How do they interact? How do forces change with energy or temperature? How has the universe evolved? University of Buffalo Colloquium

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

8. q q qq q q qq qq relative strength asymptotic freedom confinement distance energy density, temperature Quantum Chromodynamics - QCD Gauge field carries the charge University of Buffalo Colloquium

9. 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 University of Buffalo Colloquium

10. Why do we believe QCD is a good description of the strong interaction? No direct observation of quarks: confinement University of Buffalo Colloquium

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

12. e+e- Zo  qq e+e- Zo  qqg Why do we believe QCD is a good description of the strong interaction? Event shapes University of Buffalo Colloquium

13. Why do we believe QCD is a good description of the strong interaction? Measure the coupling P. Burrows, SLAC-PUB7434, 1997 University of Buffalo Colloquium

14. Strong interaction is part of our heritage University of Buffalo Colloquium

15. qq qq qq qq qq qq Chiral symmetry: the “other” source of mass A naïve view … Quark condensate QCD vacuum q University of Buffalo Colloquium

16. University of Buffalo Colloquium

17. Relativistic heavy ions • 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 • 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)!! University of Buffalo Colloquium

18. The view from above University of Buffalo Colloquium

19. STAR University of Buffalo Colloquium

20. Au-Au collision in the STAR detector University of Buffalo Colloquium

21. Isometric of PHENIX Detector University of Buffalo Colloquium

22. Brahms experiment From F.Videbœk University of Buffalo Colloquium

23. The PHOBOS Detector (2001) ZDC Paddle Trigger Counter Time of Flight Spectrometer Vertex Octagon Ring Counters Cerenkov y f x q z 1m • 4p Multiplicity Array • - Octagon, Vertex & Ring Counters • Mid-rapidity Spectrometer • TOF wall for high-momentum PID • Triggering • Scintillator Paddles Counters • Zero Degree Calorimeter (ZDC) 137000 silicon pad readout channels University of Buffalo Colloquium

24. Central Part of the Detector (not to scale) 0.5m University of Buffalo Colloquium

25. Au-Au event in the PHOBOS detector University of Buffalo Colloquium

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

27. Terminology: angles Beamline University of Buffalo Colloquium

28. Terminology: angles Pseudorapidity =  = Lorentz invariant angle with repect to the beampipe -3 +3 -2 +2 +1 Beamline -1 0 University of Buffalo Colloquium

29. Terminology: angles  = azimuthal angle about the beampipe Beamline University of Buffalo Colloquium

30. peripheral collisions central collisions Terminology: centrality Nch “Spectators” “Participants” Zero-degreeCalorimeter 6% “Spectators” Paddle Counter Npart Thanks to P. Steinberg for constructing much of this slide University of Buffalo Colloquium

31. Signatures/observables • 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 Measured value Energy density or number of participants Each variable has different experimental systematics and model dependences on extraction and interpretation MUST CORRELATE VARIABLES University of Buffalo Colloquium

32. RHIC operation Run 1 12 June, 2000: 1st Collisions @ s = 56 AGeV 24 June, 2000: 1st Collisions @ s = 130 AGeV July 2001: 1st Collisions @ s = 200 AGeV Dec. 23, 2002: 1st d-Au collisions @ s = 200 AGeV Run 2 Run 3 Run 2: Peak Au-Au luminosity = 5x1026 cm-2s-1 Design Au-Au luminosity = 2x1026 cm-2s-1 Ave luminosity for last week of ‘02 run = 0.4x1026 cm-2s-1 University of Buffalo Colloquium

33. From Thomas Roser University of Buffalo Colloquium

34. From Thomas Roser University of Buffalo Colloquium

35. Results from RHIC! • Energy flow, Particle multiplicity  high energy density • Particle production  QCD is QCD is QCD • Large flow, species yields  equilibration/thermalization • Spectra, flow, jets  Jet quenching • Not talking about Bose-Einstein correlations, strangeness enhancement, J/ suppression, balance function, direct photon production, mass shifts, width shifts, etc. University of Buffalo Colloquium

36. Experimental results at RHIC imply 5 GeV/fm3 4.6 GeV/fm3 Energy density of proton and lattice QCD calculations Expect deconfinement phase transition to occur at an energy density of 1-2 GeV/fm3 PHENIX Collaboration, PRL 87 (2001) 052301 Assumes R=size of Au nucleus and To=1fm/c University of Buffalo Colloquium

37. 200 GeV 19.6 GeV 130 GeV PHOBOS PHOBOS PHOBOS Preliminary dN/dh Typical systematic band (90%C.L.) h h h Basic systematics of particle production PHOBOS Data on dN/dh in Au+Auvs Centrality and s University of Buffalo Colloquium

38. PHOBOS Au+Au dNch/dh dNch/dh ¢/<Npart> 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. PHOBOS Au+Au 19.6 GeV is preliminary 19.6 GeV is preliminary Systematic errors not shown Energy Dependence of Central dN/dh Scale by Npart/2 & shift to h¢=h- ybeam The “fragmentation region” extent grows with sNN University of Buffalo Colloquium

39. Universality of particle production (Mueller 1983) From P.Steinberg University of Buffalo Colloquium

40. Universality of particle production A+A e+e- pp/pp From P.Steinberg University of Buffalo Colloquium

41. Universality of particle production Universality pp e+e- Au+Au p+pp+X : From P.Steinberg University of Buffalo Colloquium

42. Elliptic flow Collision region is an extruded football/rugby ball shape Central Peripheral University of Buffalo Colloquium

43. Elliptic flow 9 12 Number of particles 6 3 12 3 6 9 12 University of Buffalo Colloquium

44. 9 12 6 3 Number of Particles 12 3 6 9 12 University of Buffalo Colloquium

45. Elliptic flow b (reaction plane) Determine to what extent is the initial state spatial/momentum anisotropy is mapped into the final state. dN/d(f -YR ) = N0 (1 + 2V1cos (f-YR) + 2V2cos (2(f-YR) + ... ) University of Buffalo Colloquium

46. Elliptic Flow at 130 GeV Hydrodynamic limit STAR: PRL86 (2001) 402 PHOBOS preliminary Thanks to M. Kaneta (PHOBOS : Normalized Paddle Signal) University of Buffalo Colloquium

47. Hydro describes low pt vs. particle mass, fails at high pt and high- T. Hirano Flow vs Pt and  (consider velocity and early, self-quenching asymmetry) University of Buffalo Colloquium

48. F. Becattini, hep-ph/9701275 LEP 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 Tc University of Buffalo Colloquium

49. Spectra The fun starts when one compares this to pp spectra 0.2<yp<1.4 STAR results, shown at QM02 University of Buffalo Colloquium

50. _ Comparing Au+Au and ppSpectra • Production of high pT particles dominated by hard scattering • High pT yield prop. to Ncoll (binary collision scaling) • Compare to pp spectra scaled up by Ncoll • Violation of Ncoll scaling observed at 130GeV (PHENIX/STAR) • Jet quenching? Au+Au _ University of Buffalo Colloquium