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The Science with RHIC and Its Upgrade

The Science with RHIC and Its Upgrade. W.A. Zajc Columbia University IUPAP WG-9 Symposium July 2-3, 2010, TRIUMF.

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The Science with RHIC and Its Upgrade

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  1. The Science with RHIC and Its Upgrade W.A. ZajcColumbia UniversityIUPAP WG-9 SymposiumJuly 2-3, 2010, TRIUMF 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 W.A. Zajc

  2. Assertion W.A. Zajc

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

  4. U.S. Long Range Planning in Nuclear Science • A source of considerable community pride • Something we’re good at • The plans are ‘resource burdened’ • We’ve been at it for a long time: 1983 1989 1996 2002 2007 W.A. Zajc

  5. We’re Good at It and Have Been For a Long Time • A case in point – the Relativistic Heavy Ion Collider (RHIC) • 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.” • 2000: RHIC begins operations • 2005: Announcement of major discoveries at RHIC W.A. Zajc

  6. Discovery2005 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. W.A. Zajc

  8. The RHIC Discovery W.A. Zajc

  9. A RHIC Mission The RHIC Discovery RHIC’s Bounty W.A. Zajc

  10. Lg SqDq SqLq dq DG A RHIC Mission Understand the spin structure of the proton W.A. Zajc

  11. RHIC Spin • RHIC is the world’s only polarized proton collider: W.A. Zajc

  12. RHIC Spin • RHIC is the world’s only polarized proton collider: W.A. Zajc

  13. RHIC Spin • RHIC is the world’s only polarized proton collider. • Use pQCD to study how the proton spinis distributed among its constituents: W.A. Zajc

  14. pQCD at RHIC (I) • Establishing the validity of pQCD at RHIC energies essential to both the spin and the heavy ion programs: STAR: PRL97, 252001 (2006) PHENIX: PRD76051106 (2007) W.A. Zajc

  15. pQCD at RHIC (II) • Spin: pQCD is • absolutely essential for reliable, quantitative extraction of polarized distribution functions(next slide) • Heavy ions: pQCD is • absolutely essential for reliable, quantitativemeasurement of “jet quenching” W.A. Zajc

  16. Gluon Contribution DG to Proton Spin • Dg(x)  g+(x) – g-(x) • In global analysis, RHIC data already play dominant role in constraining Dg(x) for x < 0.2 : • Future measurementswith > x10 increase in integrated luminosity • Greatly reduced errors in putative(?) negative Dg(x) • Photons, heavy flavor • Di-hadron, jet-jet, g-jetto provide directmeasurement ofDg(x) x-dependence 2001 2005 2008 RHIC 2012 ? W.A. Zajc

  17. Angular Momentum Contributions to Proton Spin • Observation of large single spin transverse asymmetries at large |xF| at RHIC: • Potential to understandorbital motion of partonsin the proton • In particular • Test “non-universality”of Sivers function • Clear prediction of signchange between DIS and Drell-Yan(D-Y to be measured at RHIC, luminosity hungry!) W.A. Zajc

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

  19. A RHIC Mission W.A. Zajc

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

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

  22. 2010 – First Temperature Measurement • PHENIX, PRL 104:132301, 2010 • Ti ~ 300-500 MeV W.A. Zajc

  23. Clearly in Deconfined Regime • Ti ~ 400 MeV quark and gluon d.o.f. “dominant” W.A. Zajc

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

  26. Perfect Fluids • Perfect fluids are characterized by low viscosity. • Low viscosity requires strong coupling. W.A. Zajc

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

  28. RHIC and the Phases of Nuclear Matter W.A. Zajc

  29. Heavy Ions at the LHC • Offers an unprecedented increase in energy: • RHIC sNN = 0.2 TeV • LHC sNN = 5.5 TeV • 5.5 / 0.2 = 27.5 (!) • Estimate for change in initial temperature Ti : • Ti(LHC) = (27.5)1/4 Ti(RHIC) ~ 2.3 Ti(RHIC) • N.B.: LHC matter will still evolve through ‘RHIC’ temperature regime W.A. Zajc

  30. RHIC and LHC RHIC LHC W.A. Zajc

  31. Two Scenarios • Scenario 1: Matter at LHC similar to RHIC • LHC will study with much higher Q2 probes • New observables  new discoveries • RHIC will study with greater flexibility in • Running time, energies and species • Baseline (p+p) measurements • Control (p+A, d+A) measurements • Scenario 2: LHC weakly-coupled, RHIC strongly-coupled • LHC will probe fundamentally new regime • RHIC uniquely able to study strongly-coupled QGP W.A. Zajc

  32. The Future RHIC Program • “We recommend implementation of the RHIC II luminosity upgrade… • Underway! (technological breakthrough) • ~1/7 the cost • ~ 4 years early • …together with detector improvements … • Underway • …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 W.A. Zajc

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

  34. The “RHIC II” Luminosity Upgrade • 1/7 the cost and 4 years early ? • 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 14 Jan 2010 W.A. Zajc

  35. Building On Success • First decade of RHIC Operations: dramatic successes pb-1 Achieved peak luminosities (100 GeV, nucl.-pair): Au–Au 1551030 cm-2s-1 p–p 501030 cm-2s-1 Other large hadron colliders (scaled to 100 GeV): Tevatron (p – pbar) 351030 cm-2s-1 LHC (p – p, design) 1401030 cm-2s-1 Initial Discoveries Operated modes (beam energies): Au–Au 3.8, 4.6, 5.8, 10, 32, 65, 100 GeV/n d–Au* 100GeV/n Cu–Cu 11, 31, 100 GeV/n p–p 11, 31, 100, 250 GeV Planned or possible future modes: Au – Au 2.5 GeV/n (~ AGS cm energy) p – Au* 100 GeV/n(*asymmetric rigidity) W.A. Zajc

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

  37. “… to determine the properties of this new state of matter.” • Example: How strong is the coupling ? • Surprising discovery: heavy flavor (charm, perhaps bottom) • Loses energy in medium • Flows with the medium despite MHF >> TQGP • The Si Vertex upgrades+ “RHIC II” luminositieswill separatethe contributions of b and c quarks to this result W.A. Zajc

  38. QCD Condensed Matter • “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 me/mp . • “RHIC II” goal: to measure medium properties • Examples: • Debye screening length • Equation of state • Jet quenching ( dE/dx ) • Shear viscosity • Bulk viscosity W.A. Zajc

  39. Shear Viscosity • The ultimate “outreach” of the ultimate condensed matter physics • Conjectured quantumbound of 1 / 4p • We need to firmlyestablish RHIC point(s) W.A. Zajc

  40. Current Status of h/s Extraction • To do: • Vary • s • Mass • Probe(c, b) • Shape( 238U ) • Allenabled by upgraded RHIC Chaudhuri, arXiv:010.0979 Chaudhuri, arXiv:0909.0391 Luzum and Romatschke, arXiv:0804:4015 W.A. Zajc

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

  42. The QCD Critical Point • The landscape’skey feature . • RHIC uniquely bridges GSI  LHC W.A. Zajc

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

  44. A RHIC Mission The RHIC Discovery W.A. Zajc

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

  46. Gluon Saturation • Glue dominates the low-x structure of nucleons: • In nuclei, saturation scale Qs2 ~ A1/3 Q02. • Naturally studied in • p+A and/or d+A collisions • Upgrades to STAR and PHENIX enable “3rd” RHIC program dedicated to saturation physics • Natural connection to • Initial state in A+A at RHIC (and LHC) • Electron Ion Collider (see talk by A. Deshpande) W.A. Zajc

  47. QCD Surprises • Local strong parity violation ? STAR PRL 103:251601,2009 W.A. Zajc

  48. Local Strong Parity Violation? • Requires • Strong magnetic field (~1017 G) • Deconfined quarks (plausible) • QCD topological charge (TBD) • Discovery requires • Elimination of allmundane effects • Excitation function • Study in • Isobaric pairs (e.g., 9644Ru and 9640Zr) • Asymmetric collisions (e.g., Cu+Au) W.A. Zajc

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

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

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