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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 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
Assertion W.A. Zajc
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
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
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
Discovery2005 W.A. Zajc
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
The RHIC Discovery W.A. Zajc
A RHIC Mission The RHIC Discovery RHIC’s Bounty W.A. Zajc
Lg SqDq SqLq dq DG A RHIC Mission Understand the spin structure of the proton W.A. Zajc
RHIC Spin • RHIC is the world’s only polarized proton collider: W.A. Zajc
RHIC Spin • RHIC is the world’s only polarized proton collider: W.A. Zajc
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
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
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
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
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
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
A RHIC Mission W.A. Zajc
A RHIC Mission The RHIC Discovery “Perfect Liquid” behavior of the quark-gluon plasma W.A. Zajc
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
2010 – First Temperature Measurement • PHENIX, PRL 104:132301, 2010 • Ti ~ 300-500 MeV W.A. Zajc
Clearly in Deconfined Regime • Ti ~ 400 MeV quark and gluon d.o.f. “dominant” W.A. Zajc
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
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
Perfect Fluids • Perfect fluids are characterized by low viscosity. • Low viscosity requires strong coupling. W.A. Zajc
Perfect Fluids • Perfect fluids are characterized by low viscosity. • Low viscosity requires strong coupling. • Precisely the region studied with RHIC energies. W.A. Zajc
RHIC and the Phases of Nuclear Matter W.A. Zajc
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
RHIC and LHC RHIC LHC W.A. Zajc
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
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
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
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
Building On Success • First decade of RHIC Operations: dramatic successes pb-1 Achieved peak luminosities (100 GeV, nucl.-pair): Au–Au 1551030 cm-2s-1 p–p 501030 cm-2s-1 Other large hadron colliders (scaled to 100 GeV): Tevatron (p – pbar) 351030 cm-2s-1 LHC (p – p, design) 1401030 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
“… 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
“… 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
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
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
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
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
The QCD Critical Point • The landscape’skey feature . • RHIC uniquely bridges GSI LHC W.A. Zajc
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
A RHIC Mission The RHIC Discovery W.A. Zajc
A RHIC Mission The RHIC Discovery RHIC’s Bounty Potential to study even more than what has been presented here. W.A. Zajc
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
QCD Surprises • Local strong parity violation ? STAR PRL 103:251601,2009 W.A. Zajc
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
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
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