1. The Science with RHIC and Its Upgrade W.A. Zajc Columbia University IUPAP WG-9 Symposium July 2-3, 2010, TRIUMF 02-Jul-10 W.A. Zajc With my explicit thanks to E. Aschenauer, A. Deshpande, J. Dunlop, W. Fischer, J. Nagle, E. O’Brien, K. Rajagopal, T. Roser, S. Vigdor ; and implicit thanks to all my colleagues at RHIC

2. Assertion 02-Jul-10 W.A. Zajc

3. Fact l QCD is our prototypical non-Abelian gauge theory  Amenable to experimental study at both strong and weak coupling  Deep connections to other gauge theories l RHIC is the only facility dedicated to the study of QCD  In the thermal regime  Using perturbative probes to study non-perturbative phenomena 02-Jul-10 W.A. Zajc

4. U.S. Long Range Planning in Nuclear Science l A source of considerable community pride l Something we’re good at l The plans are ‘resource burdened’ l We’ve been at it for a long time: 02-Jul-10 W.A. Zajc 19831989199620022007

5. We’re Good at It and Have Been For a Long Time l A case in point – the Relativistic Heavy Ion Collider (RHIC) l 1983 Plan:  “We identify a relativistic heavy ion collider as the highest priority for the next major facility to be constructed, with the potential for addressing a new scientific frontier of fundamental importance.” l 2000: RHIC begins operations l 2005: Announcement of major discoveries at RHIC 02-Jul-10 W.A. Zajc

6. Discovery 2005 02-Jul-10 W.A. Zajc

7. 2007 Long Range Plan Recommendation #4  The experiments at the Relativistic Heavy Ion Collider have discovered a new state of matter at extreme temperature and density — a quark-gluon plasma that exhibits unexpected, almost perfect liquid dynamical behavior. We recommend implementation of the RHIC II luminosity upgrade, together with detector improvements, to determine the properties of this new state of matter. We recommend implementation of the RHIC II luminosity upgrade, together with detector improvements, to determine the properties of this new state of matter. 02-Jul-10 W.A. Zajc

8. 02-Jul-10 W.A. Zajc The RHIC Discovery

9. A RHIC Mission 02-Jul-10 W.A. Zajc The RHIC Discovery RHIC’s Bounty

10. A RHIC Mission Understand the spin structure of the proton 02-Jul-10 W.A. Zajc qqqqqqqq GGGG LgLgLgLg qLqqLqqLqqLq qqqq

11. RHIC Spin l RHIC is the world’s only polarized proton collider: 02-Jul-10 W.A. Zajc

12. RHIC Spin l RHIC is the world’s only polarized proton collider: 02-Jul-10 W.A. Zajc

13. RHIC Spin l RHIC is the world’s only polarized proton collider. l Use pQCD to study how the proton spin is distributed among its constituents: 02-Jul-10 W.A. Zajc

14. pQCD at RHIC (I) 02-Jul-10 W.A. Zajc STAR: PRL97, 252001 (2006) PHENIX: PRD76 051106 (2007) l Establishing the validity of pQCD at RHIC energies essential to both the spin and the heavy ion programs:

15. pQCD at RHIC (II) l Spin: pQCD is  absolutely essential for reliable, quantitative extraction of polarized distribution functions (next slide) l Heavy ions: pQCD is  absolutely essential for reliable, quantitative measurement of “jet quenching” 02-Jul-10 W.A. Zajc

16. Gluon Contribution  G to Proton Spin 02-Jul-10 W.A. Zajc RHIC  g(x)  g + (x) – g - (x)  g(x)  g + (x) – g - (x) In global analysis, RHIC data already play dominant role in constraining  g(x) for x < 0.2 : In global analysis, RHIC data already play dominant role in constraining  g(x) for x < 0.2 : l Future measurements with > x10 increase in integrated luminosity  Greatly reduced errors in putative(?) negative  g(x)  Photons, heavy flavor  Di-hadron, jet-jet,  -jet to provide direct measurement of  g(x) x-dependence 2001 2005 2008 2012 ?

17. Angular Momentum Contributions to Proton Spin l Observation of large single spin transverse asymmetries at large |x F | at RHIC: l Potential to understand orbital motion of partons in the proton l In particular  Test “non-universality” of Sivers function  Clear prediction of sign change between DIS and Drell-Yan (D-Y to be measured at RHIC, luminosity hungry!) 02-Jul-10 W.A. Zajc

18. Sea Quark Contribution to Proton Spin l Via “self-analyzing” W production (!) l 2009: 500 Gev run: proof of principle (~10 pb -1 ) l First spin results (!) l Future:  10 pb -1  300 pb -1  PHENIX  trigger  STAR GEM tracker 02-Jul-10 W.A. Zajc

19. A RHIC Mission 02-Jul-10 W.A. Zajc

20. A RHIC Mission 02-Jul-10 W.A. Zajc The RHIC Discovery “Perfect Liquid” behavior of the quark-gluon plasma

21. Expectations circa 2000 As encoded in the Nuclear Physics Wall Chart, http://www.lbl.gov/abc/wallchart/ RHIC would create a quark-gluon plasma; a “gas” of weakly interacting quarks and gluons 02-Jul-10 W.A. Zajc

22. 2010 – First Temperature Measurement 02-Jul-10 W.A. Zajc l PHENIX, PRL 104:132301, 2010 l T i ~ 300-500 MeV

23. Clearly in Deconfined Regime l T i ~ 400 MeV  quark and gluon d.o.f. “dominant” 02-Jul-10 W.A. Zajc

24. But - The Quark-Gluon Plasma is Not a Gas l Prejudice circa 2000:  Protons and neutrons would ‘sublimate’ to a gas of quarks and gluons  Much like dry ice l Discovery circa 2005  The quark-gluon plasma is a nearly perfect liquid  Something like regular ice to water 02-Jul-10 W.A. Zajc

25. Long Range Plan Recommendation  The experiments at the Relativistic Heavy Ion Collider have discovered a new state of matter at extreme temperature and density — a quark-gluon plasma that exhibits unexpected, almost perfect liquid dynamical behavior. We recommend implementation of the RHIC II luminosity upgrade, together with detector improvements, to determine the properties of this new state of matter. We recommend implementation of the RHIC II luminosity upgrade, together with detector improvements, to determine the properties of this new state of matter. 02-Jul-10 W.A. Zajc

26. Perfect Fluids l Perfect fluids are characterized by low viscosity. l Low viscosity requires strong coupling. 02-Jul-10 W.A. Zajc

27. Perfect Fluids l Perfect fluids are characterized by low viscosity. l Low viscosity requires strong coupling. l Precisely the region studied with RHIC energies. 02-Jul-10 W.A. Zajc

28. RHIC and the Phases of Nuclear Matter 02-Jul-10 W.A. Zajc

29. Heavy Ions at the LHC l Offers an unprecedented increase in energy:  RHIC  s NN = 0.2 TeV  LHC  s NN = 5.5 TeV  5.5 / 0.2 = 27.5 (!) l Estimate for change in initial temperature T i :  T i (LHC) = (27.5) 1/4 T i (RHIC) ~ 2.3 T i (RHIC)  N.B.: LHC matter will still evolve through ‘RHIC’ temperature regime 02-Jul-10 W.A. Zajc

30. RHIC and LHC 02-Jul-10 W.A. Zajc RHICLHC

31. Two Scenarios l Scenario 1: Matter at LHC similar to RHIC  LHC will study with much higher Q 2 probes o New observables  new discoveries  RHIC will study with greater flexibility in o Running time, energies and species o Baseline (p+p) measurements o Control (p+A, d+A) measurements l Scenario 2: LHC weakly-coupled, RHIC strongly-coupled  LHC will probe fundamentally new regime  RHIC uniquely able to study strongly-coupled QGP 02-Jul-10 W.A. Zajc

32. The Future RHIC Program l “We recommend implementation of the RHIC II luminosity upgrade…  Underway! (technological breakthrough) o ~1/7 the cost o ~ 4 years early l …together with detector improvements …  Underway l …to determine the properties of this new state of matter.”  Thermodynamics, equation of state of perfect liquid  Search for the critical point in its phase diagram 02-Jul-10 W.A. Zajc

33. The “RHIC II” Luminosity Upgrade l 1/7 the cost and 4 early ? l 1/7 the cost and 4 years early ? l Yes !  Breakthrough – stochastic cooling in a bunched collider 02-Jul-10 W.A. Zajc Y h+v pickups B h+v kickers B h+v pickups Y h+v kickers

34. The “RHIC II” Luminosity Upgrade l 1/7 the cost and 4 early ? l 1/7 the cost and 4 years early ? l Yes !  Breakthrough – stochastic cooling in a bunched collider  2010: RHIC operates at ~ 10 x design luminosity  Full stochastic cooling (2012) provides 20 x design luminosity 02-Jul-10 W.A. Zajc 14 Jan 2010

35. Building On Success l First decade of RHIC Operations: dramatic successes 02-Jul-10 W.A. Zajc Operated modes (beam energies): Au–Au 3.8, 4.6, 5.8, 10, 32, 65, 100 GeV/n d–Au* 100 GeV/n Cu–Cu11, 31, 100 GeV/n p  –p  11, 31, 100, 250 GeV Planned or possible future modes: Au – Au2.5 GeV/n (~ AGS cm energy) p  – Au*100 GeV/n (*asymmetric rigidity) Achieved peak luminosities (100 GeV, nucl.-pair): Au–Au 155  10 30 cm -2 s -1 p  –p  50  10 30 cm -2 s -1 Other large hadron colliders (scaled to 100 GeV): Tevatron (p – pbar) 35  10 30 cm -2 s -1 LHC (p – p, design)140  10 30 cm -2 s -1 Initial Discoveries pb -1

36. “… together with detector improvements …” l Underway. l Examples:  PHENIX o Muon trigger (W’s) o VTX (central Si) o FVTX (forward Si)  STAR o Forward GEM tracker (W’s) o Heavy Flavor Tracker 02-Jul-10 W.A. Zajc

37. “… to determine the properties of this new state of matter.” l Example: How strong is the coupling ? l Surprising discovery: heavy flavor (charm, perhaps bottom)  Loses energy in medium  Flows with the medium despite M HF >> T QGP despite M HF >> T QGP l The Si Vertex upgrades + “RHIC II” luminosities will separate the contributions of b and c quarks to this result 02-Jul-10 W.A. Zajc

38. QCD Condensed Matter l “Perfect Liquid” – a new state of matter (energy)  One that emerges from a fundamental Lagrangian  The ultimate condensed matter physics  No (?) dependence on ‘accidental’ scales like m e /m p. l “RHIC II” goal: to measure medium properties l Examples:  Debye screening length  Equation of state  Jet quenching ( dE/dx )  Shear viscosity  Bulk viscosity 02-Jul-10 W.A. Zajc

39. l The ultimate “outreach” of the ultimate condensed matter physics Conjectured quantum bound of 1 / 4  Conjectured quantum bound of 1 / 4  l We need to firmly establish RHIC point(s) Shear Viscosity 02-Jul-10 W.A. Zajc

40. Current Status of  /s Extraction l To do: l Vary ss  Mass  Probe (c, b)  Shape ( 238 U ) l All enabled by upgraded RHIC 02-Jul-10 W.A. Zajc Chaudhuri, arXiv:010.0979 Luzum and Romatschke, arXiv:0804:4015 Chaudhuri, arXiv:0909.0391

41. The Phases of QCD 02-Jul-10 W.A. Zajc l Transition to QGP at highest RHIC energy is “infinite order” l First-order phase transition expected at lower energy. l WHERE ?

42. The QCD Critical Point 02-Jul-10 W.A. Zajc l The landscape’s key feature. l RHIC uniquely bridges GSI  LHC

43. The QCD Critical Point 02-Jul-10 W.A. Zajc l The landscape’s key feature. l RHIC uniquely bridges GSI  LHC l Requires RHIC to be run as low energy collider l Search via non-monotonic trends in fluctuations l Search underway l Precision may await further luminosity upgrades

44. A RHIC Mission 02-Jul-10 W.A. Zajc The RHIC Discovery

45. A RHIC Mission 02-Jul-10 W.A. Zajc The RHIC Discovery RHIC’s Bounty Potential to study even more than what has been presented here.

46. Gluon Saturation 02-Jul-10 W.A. Zajc l Glue dominates the low-x structure of nucleons: l In nuclei, saturation scale Q s 2 ~ A 1/3 Q 0 2. l Naturally studied in  p+A and/or d+A collisions  Upgrades to STAR and PHENIX enable “3 rd ” RHIC program dedicated to saturation physics l Natural connection to  Initial state in A+A at RHIC (and LHC)  Electron Ion Collider (see talk by A. Deshpande)

47. QCD Surprises l Local strong parity violation ? 02-Jul-10 W.A. Zajc STAR PRL 103:251601,2009

48. Local Strong Parity Violation? l Requires Strong magnetic field (~10 17 G) Deconfined quarks (plausible)  QCD topological charge (TBD) l Discovery requires  Elimination of all mundane effects  Excitation function  Study in o Isobaric pairs (e.g., 96 44 Ru and 96 40 Zr) o Asymmetric collisions (e.g., Cu+Au) 02-Jul-10 W.A. Zajc

49. The Big Picture l The strongly-coupled fluid at RHIC has created unique ties to other fields: 02-Jul-10 W.A. Zajc AdS/QCD Perfect liquid AdS/CFT Prediction of  /s bound AdS/CMT Cold atomic gases Strongly correlated electrons

50. The Bigger Picture l The AdS/CFT correspondence forges a fascinating link between  Semi-classical gravity  Strongly-coupled gauge theories l In some sense, it ‘works best’ when  Coupling is as strong as possible  System is thermal l RHIC ! 02-Jul-10 W.A. Zajc

51. Summary l RHIC’s unparalleled versatility  Has led to major discoveries  Provides a dedicated environment for study of o Thermal QCD o Spin structure of proton o Saturation physics l Recent advances in  Luminosity and accelerator capability  Detector upgrades establish a future program of extraordinary promise. establish a future program of extraordinary promise. 02-Jul-10 W.A. Zajc

52. Thank You ! With my explicit thanks to E. Aschenauer, A. Deshpande, J. Dunlop, W. Fischer, J. Nagle, E. O’Brien, K. Rajagopal, T. Roser, S. Vigdor ; and implicit thanks to all my colleagues at RHIC 02-Jul-10 W.A. Zajc