1. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Future Perspective of Heavy Ion Physics at the QCD Lab Outline Where are we now (physics-wise) at RHIC? Where are we going (physics-wise)? What will it take to get there? What is the role of the QCD Lab in this field (with RHIC & LHC)?

2. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Where are we now (physics-wise) at RHIC?

3. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 After 5 Years of RHIC → Experimental Evidence for an sQGP After the completely unexpected RHIC v2 results on DAY 1 !  “perfect” fluid flow came the STAR & PHENIX particle identified flow  appropriate dynamical approach  QGP EoS,, quark coalescence then the thermalization as seen in all particle ratios fit by thermal models  T = 177 MeV ~ T c (lattice QCD) Next the remarkable STAR & PHENIX suppression of high p T hadrons  extreme gluon/energy densities (verifying initial PHENIX & STAR  >>  c ) observation of the spectacular disappearance of the away-side jet  large opacity  strongly-interacting QGP (sQGP) flow of heavy quarks and their suppression at high p T  similarity with light quarks defies theoretical predictions……

4. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Where are we going (physics-wise)?

5. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Where are we headed at RHIC? PHENIX & STAR - “continue to establish presence & properties of sQGP”  Systematic study (vs.…) of soft observables  Electromagnetic Probes  Heavy Flavors  Hard Probes - jets PHENIX & STAR: “will continue upgrading detector capabilities”  Increase triggering capabilities and DAQ rates  Expand apertures  Add new capabilities (micro-vertexing, low-mass di-leptons, high p T PID) Direct  – thermal radiation, shadowing Virtual  (e + e - ) - chiral restoration via low mass di-leptons STAR HFT PHENIX MVTXPHENIX HBDPHENIX Aerogel STAR ToF Open charm, charmonium ( ,  ’) spectroscopy Open beauty, bottomonium ( ,  ’,  ’’) spectroscopy Flavor-tagged jets Deconfinement Initial T via leading particles  -jet, D-jet, B-jet, topology (jet energy)! Parton energy loss Properties of QGP Response of medium Low  physics require RHIC luminosity upgrade +

6. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 PHENIX & STAR - “continue to establish presence & properties of sQGP”  Systematic study (vs.…) of soft observables  Electromagnetic Probes  Heavy Flavors  Hard Probes - jets PHENIX & STAR: “will continue upgrading detector capabilities”  Increase triggering capabilities and DAQ rates  Expand apertures  Add new capabilities (micro-vertexing, low-mass di-leptons, high p T PID) Parton energy loss Properties of QGP Response of medium Low  physics require RHIC luminosity upgrade + Where are we headed at RHIC? Direct  – thermal radiation, shadowing Virtual  (e + e - ) - chiral restoration via low mass di-leptons STAR HFT PHENIX MVTXPHENIX HBDPHENIX Aerogel STAR ToF Open charm, charmonium ( ,  ’) spectroscopy Open beauty, bottomonium ( ,  ’,  ’’) spectroscopy Flavor-tagged jets Deconfinement Initial T via leading particles  -jet, D-jet, B-jet, topology (jet energy)! How far do the RHIC detector upgrades get us?

7. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 QCD Phase Diagram 300 350 400 250 200 150 100 50 0 T (MeV) LHC initial stateRHIC initial states Evolution - RHIC, LHC? Differences –Initial temperatures –System lifetimes –Evolution? Similarities –Final stages of evolution Entire evolution different! –Jet propagation –Resulting energy deposition –Quarkonium melting

8. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Open Questions at RHIC What are the degrees of freedom in the evolution at RHIC?  Can we determine the constituents as a function of energy density (or T)? sQGP & its evolution Initial T? (  HBT) Deconfinement T c (Quarkonium melting) Constituents (partons, quasi-bound states, pre-hadrons...) Parton density (jet tomography, flavor, intra-, inter-jet correlations) Response to energy deposition Bulk properties Equation of State Chiral symmetry restoration? LHC Shuryak

9. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Future Systematic Studies of Soft Observables at Establish Presence and Properties of the QGP! When can we answer with confidence following questions…..

10. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 The sQGP Phase Transition Is system thermalized? On what timescale ? Can we determine the temperature? Nature of phase transition? Establish transport & diffusion coefficients → need microscopic transport Elliptic flow & R AA of D & B mesons → requires luminosity Tri-critical point? Near  b freezout ~ T c, √s ~ 25 GeV (not accessible at LHC) Vary √s search for enhancement in E-by-E fluctuations in and baryon number → more run-time or luminosity. What is the EoS ? Connection with thermodynamic properties of QGP on lattice PID elliptic flow & PID spectra Effective degrees of freedom versus multiplicity → deconfinement from lattice QCD plot (  vs T)

11. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Properties of sQGP & Evolving Medium Temperature of medium? Already have chemical T c - particle ratios Thermal photons - First results from PHENIX…. Low p T  spectra with ~5% error bars – data on tape sufficient? How does medium respond? Speed of sound and color di-electric constant Trigger jet and away-side correlations Mach shockwaves, Cherenkov radiation PID intra-jet correlations What is hadronization, i.e. how is mass generated? Effect of chirally-restored medium? Chiral partners? Fragmentation PID intra-jet correlations

12. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 The sQGP – a Perfect Fluid? How perfect is our fluid? Characteristics of medium & dissipative effects → viscosity, heat capacity, speed of sound, diffusion coefficients Different quark N fluctuations, v 2, R AA → diffusion coefficients Ideal hydro → zero viscosity → need viscous hydro calculation What is zero viscosity? Much less than that of water! AdS/CFT limit! Flow in U + U and at LHC vs hydro limit! Study away from mid-rapidity (more viscous and less thermal) Study details of light/strange, charm, beauty quarks propagation through the nearly perfect fluid! Should be different? My view – “Theory needs to catch up!” “We must identify more sensitive observables” Can we get bulk properties from lattice? Bulk (transport) properties from dynamical (or hybrid) model?

13. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Synopsis for sQGP QGP discovery (without equivocation)! Many properties of QGP will/still to be determined. Still to do: Establish constituents of sQGP state (EOS)? Use heavy flavors, flavor-triggered jets & jets at larger p T ! - as probe of sQGP and response of medium Study onium for convincing picture of deconfinement? Tc? And ….. whatever happened to chiral restoration?

14. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Jets at

15. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Compelling “Jet Physics” for RHIC & QCD Lab (in LHC-era)* F QGP (  g QGP ) = f initial (√s, A 1 +A 2, b, x 1, x 2, Q 2 )  f QGP (p T ,y ,  ,p T jet,y jet,  jet,flavor jet,  flow ) Characterizing the sQGP using partons * not complete at LHC! “Jet” Probes –High p T identified (light-, s-, c-, b-quark) particles fragmentation function modification and flavor dependence –  -jet,  - high-p T identified particle, particle-particle, di-jets parton energy loss in medium, response of medium fragmentation function modification, di-hadron fragmentation functions Measure over Multi-Parameter Space: –Energy - √s –Geometry - system A 1 +A 2, impact parameter b –Rapidity (x-dependence) to forward angles –Transverse momentum of jet / leading particle –Particle type (flavor) –Orientation relative to flow plane (  flow ) –Photon-tag on opposite side

16. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Detailed “Tomography” of the QGP  /parton parton flow plane F QGP (  g QGP ) = f initial (√s, A 1 +A 2, b, x 1, x 2, Q 2 )  f QGP (p T ,y ,  ,p T jet,y jet,  jet, flavor jet,  flow ) “jet Renk, HP2006 near-side Triggered jets come from near-side surface Di-hadrons penetrate core! Renk, HP2006 near-side

17. Mach cone phenomenology II Dijet rapidity correlation Trigger vertex distribution Rapidity cut effectsFlow effects on correlation Renk - Ruppert, hep-ph/0605330 Renk, nucl- th/0607035 From talk by Berndt Mueller in this Workshop

18. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Jets Broaden Significantly in Pseudorapidity! Kinematics in  and p T in pp (  +jet) Broadening in  and  pp  AA AA pp STAR results on correlations for p T < 2 GeV/c  elongation even on near-side! Large acceptance for  ’s, high p T particles, jets (energy) essential to understand jets, high p T correlations and x-dependence (esp. forward - low x)  with tracking + EMCAL (+ ….) Au+Au, 0-5% 200 GeV, |  | < 0.7 2.5 < p T (trig) < 4 GeV 2 < p T (assoc) < p T (trig)

19. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Reminder - Gluon versus Quark Jets LHC  Gluon jets Top energy RHIC p T < 20 GeV  Gluon jets p T > 20 GeV  Quark jets Lower RHIC energy transition from gluon to quark jets Utilize RHIC versatility in √s!  -jet and di-hadrons     correlations  x  x  correlations qg, gg, qq scattering 3-jet events?

20. STAR Upgrades Workshop – 2 December 2005John Harris (Yale)  + jet Direct photons p T  10 GeV/c for 1 nb -1 p T  15 GeV/c for 10 nb -1  Issues of fragmentation  ’s  Distinguish direct from frag.  ’s  How does energy loss affect this?  +jet  1% jets have leading hadron > bkgd Measure away-side frag. function AuAu (b = 0), s 1/2 = 200 GeV dN/dyd 2 p T (y=0) (GeV -2 c -3 ) q qg  STAR  +jet yields in STAR (central Au+Au – long Au + Au run): E   = 10 GeV: ~8K ch. hadrons in spectrum E   = 15 GeV: ~1K ch. hadrons in spectrum Detailed  - jet measurements* require luminosity (and increase in coverage)! XN Wang et al from STAR decadel plan Note:  -jet calibrates di-hadrons & all correlations

21. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Understanding Hadronization, Fragmentation & Medium Modification from Jet Quenching? Measure fragmentation functions in pp & modifications in AA. Study z = p hadron /p jet and x dependence : 0.2 < z < 1  7 < p < 30 GeV/c 0.1 < x < 0.001  0 <  < 3 High p T Identified particles Intra- and inter-jet particle correlations Large  acceptance  -tagged jets Each flavor parton contributes differently to fragmentation function (see Bourrely & Soffer, hep-ph/0305070) should lose different amounts of energy in opaque medium. zz  Essential for real “jet tomography” 0.2 < z < 1  7 < p < 30 GeV/c 0.1 < x < 0.001  0 <  < 3 2 GeV/c proton in 10 GeV jet Aside – effect of heavy quark propagation p/  ratio?

22. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Track-by-track High-p T Particle ID ( , K, p) and Jets  < 0.5 p q,g > 10 GeV/c Multiply pp events by factor of ~ 8 x 10 15 for AuAu events in 30 nb -1 RHIC year Jets at RHIC II (30 nb -1 )  180k at 40 GeV  +jet at high E T  for E T  = 20 GeV  19,000  + jet events (1000 @ 30 GeV) in 30 nb -1 with high p T PID over full rapidity p q,g > 10 GeV/c all  10 6 events

23. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Forward Coverage in pp, dA and AA Forward emission in hadron collider: QCD analog of low-x deep-inelastic scattering Large mid-rapidity acceptance (|  |<3.4) + forward rapidity (3.5 < |  | < 4.8) Large acceptance - full coverage of recoil parton and PID  Spin effects with rapidity interval correlations Rapidity interval (forward - mid rapidity) correlations (Mueller-Navelet Jets) low-x gluon 0.001< x g < 0.1 high-x valence quark 0.3 < x q < 0.7  Gluon Log 10 (x Gluon ) For 2  2 processes Central Tracking + calorimetry + PID forward detector frw. det.

24. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Future of Heavy Flavors at Quarkonium Physics Deconfinement QCD Thermometer Open Charm and Bottom Physics (D o, D*, D ±, D s, B) Low p T - Thermalization High p T – Tomography, Transport & other properties of QGP

25. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Quarkonium – Thermometer of Dense QCD Satz, HP2006 T melt (  ’) < T melt (  (3S)) < T melt (J/  )  T melt (  (2S)) < T RHIC < T melt (  (1S))? T RHIC > T melt (  c ), T melt (  ’), T melt (  (3S)) T LHC > T melt (J/  ), T melt (  b ), T melt (  (2S))

26. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Quarkonium Physics x F dependence: Must measure cc feed-down to J/  Production mechanism studies Nuclear absorption/shadowing studies Resolution: Acceptance  Rates Precision Tracking + Muon Detectors + EMCAL + PID Large acceptance for electrons and muons

27. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Charmonium  c Feed-down Broadening in  and p T in pp (  +jet) To measure  c decay & determine feed-down to J/   c  J/  + , must have large forward acceptance for 

28. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Heavy Flavor (Quarkonium)   e + e - resolution PHENIX (10 nb -1 )*   e + e - –with VTX (  m = 60 MeV) –w.o. VTX (  m = 170 MeV) (* 3 - 4 RHIC years of Au + Au) from PHENIX decadel plan triggered   e + e - resolution –  m = 340 MeV for 1s –  VTX improves resolution to  m = 170 MeVSTAR 2 hadron suppression factors (tradeoff - efficiency vs background) from STAR decadel plan  (1s),  (2s),  (3s) program:   e + e - resolution (PHENIX VTX)       states unresolved! Statistics?

29. RHIC-II - Heavy Flavor Yields All numbers are first rough estimates (including trigger and reconstruction efficiencies) for 12 weeks physics run (∫L eff dt ~ 18 nb -1 ) SignalRHIC Exp.ObtainedRHIC I (>2008)RHIC IILHC/ALICE + J/  → e + e  J/  →     PHENIX ~800 ~7000 3,300 29,000 45,000 395,000 9,500 740,000  → e + e -  →     STAR PHENIX ---- 830 80 11,200 1,040 2,600 8,400 B → J/  → e + e  B → J/  →     PHENIX---- 40 420 570 5,700 N/A  c → e + e    c →  +    PHENIX---- 220 8,600 2,900* 117,000* N/A D→KD→K STAR ~0.4×10 6 (S/B~1/600) 30,000** 8000 * Large backgrounds, quality uncertain as yet ** Running at 100 Hz min bias + 1 month (= year), P. Crochet, EPJdirect A1, a (2005) and private comm. T. Frawley, PANIC’05, RHIC-II Satellite Meeting

30. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Future of Electromagnetic Probes at Thermal radiation (photons) Medium modifications of vector mesons Chiral symmetry breaking Bound states in sQGP?

31. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 EM Probes (Direct Photons) Published Direct Photons from PHENIX  s NN = 200 GeV Au + Au Thermal photons (1 < p T < 4 GeV/c)? Curves pQCP for pp with binary scaling Direct photons  pQCD + binary scaling Run 4 – definitive!? Benefit from larger  L  dt ? Direct Photons from PHENIX – QM05

32. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 EM Probes (Virtual Photons via e + e - ) Medium modifications of vector mesons Chiral symmetry breaking Bound states in sQGP ? Thermal radiation May be dominated by charm R. Rapp nucl-th/0204003 Significant background issues! - e.g. Dalitz, correlated charm decays,.... requires ToF for electrons (p T > 0.2 GeV/c)  L  dt for detailed charm studies STAR requires Hadron-blind TPC (HBD)  L  dt for detailed charm studies

33. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Summary  Planned RHIC Detector Upgrades  QGP discovery and some properties  Temperatures (initial, deconfinement)? Constituents?  RHIC Luminosity Upgrade  Allows some investigation of c & b physics (transport properties, E-loss)  Allows J/  and  ’ measurements (  c depends on detectors)  Initial look at  -jet and hadronization  Some Compelling Physics Awaits Luminosity & Next Generation Det. Systems   physics (deconfinement and initial T), Detailed ystematics RHIC ↔ LHC  Detailed (PID & flavor-dependent)  -jet, intra-jet, jet-jet studies, & hadronization  Don’t forget RHIC’s other Unique Roles  Phase(s) of Matter (evolution of CGC → QGP) and investigating tri-critical point  New Spin Physics Observables  Prospects of the Unknown?  These move us in the era of heavy ions in the QCD Lab …………………..

34. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Heavy Ions in the QCD Lab – Fundamental QUESTIONS Requiring Real Answers  Degrees of Freedom of the sQGP (when, how will we get this?)  Properties of sQGP and characteristics of the phase transition (when can we describe these to others?)  Evolution of thermodynamic variables predicted from dynamical models  Fundamental properties predicted by fundamental theories - QCD, possibly AdS/CFT, others….  Color Glass Condensate & evolution to QGP (requires all of above…)  P and CP Violation near the QCD Phase Transition?  Large statistics data samples with reduced systematic errors  Origin of Mass  Understanding hadronization from fragmentation into various flavors  Chiral Symmetry Restoration  fragmentation into resonances in- and out-of-medium, chiral partners???

35. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Heavy Ions in the QCD Lab  Real answers will require next generation RHI Experiment(s) at QCD Lab  This is an absolute necessity for this field to accomplish its goals!!  One such experiment should include:  Large (nearly hermetic) acceptance  Identification of all hadrons track-by-track to large momenta  Flavor tagging capabilities track-by-track  Excellent resolution - track momenta and calorimetry (including  ’s)  Other experiments (small and/or large)?

36. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 A Comprehensive Detector Concept at the QCD Lab meters Lepton side Hadron side Parton side Basic Concept

37. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 meters Lepton side Hadron side Parton side Basic Concept Comprehensive Detector Concept at the QCD Lab meters Lepton side Hadron side Parton side Basic Concept

38. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 A Heavy Ion Detector Concept for the QCD Lab HCal and  -detectors Superconducting coil (B = 1.3T) Vertex tracking RICH HCal and  -detectors Aerogel EM Calorimeter ToF Tracking: Si, mini-TPC(?),  -pad chambers PID: RICH ToF Aerogel Forward tracking: 2-stage Si disks Forward magnet (B = 1.5T) Forward spectrometer: (  = 3.5 - 4.8) RICH EMCal (CLEO) HCal (HERA)  -absorber |  |  1.2  = 1.2 – 3.5 Central detector (|   3.4) Characteristics of Detector  Allow a Unique RHIC II Physics Program Answers for the RHI program will NOT be complete without an RHI QCD Lab program

39. John Harris (Yale) QCD Lab Workshop, BNL 17 – 22 July 2006 Heavy Ions in the QCD Lab – Fundamental QUESTIONS Requiring Real Answers  Degrees of Freedom of the sQGP (when, how will we get this?)  Properties of sQGP and characteristics of the phase transition (when can we describe these to others?)  Evolution of thermodynamic variables predicted from dynamical models  Fundamental properties predicted by fundamental theories - QCD, possibly AdS/CFT, others….  Color Glass Condensate & evolution to QGP (requires all of above…)  P and CP Violation near the QCD Phase Transition?  Large statistics data samples with reduced systematic errors  Origin of Mass  Understanding hadronization from fragmentation into various flavors  Chiral Symmetry Restoration  fragmentation into resonances in- and out-of-medium, chiral partners???