1. 1 R2D: New physics concepts for the RHIC-II phase Rene Bellwied Wayne State University Workshop on RHIC-II physics Brookhaven National Laboratory, Nov.19 th -20 th, 2004

2. 2 Expression of Interest - A Comprehensive New Detector at RHIC II P. Steinberg, T. Ullrich (Brookhaven National Laboratory) M. Calderon (Indiana University) J. Rak (Iowa State University) S. Margetis (Kent State University) M.A. Lisa, D. Magestro (Ohio State University) R. Lacey (State University of New York, Stony Brook) G. Paic (UNAM Mexico) T. Nayak (VECC Calcutta) R. Bellwied, C. Pruneau, A. Rose, S. Voloshin (Wayne State University) and H. Caines, A. Chikanian, E. Finch, J.W. Harris, M.A.C. Lamont, C. Markert, J. Sandweiss, N. Smirnov (Yale University) & RHIC-II workshop,Yale, April 16/17, 2004

3. 3 The Physics Pillars of R2D What are the detailed properties of the sQGP and what are the degrees of freedom at high densities ? What is the mechanism of hadronization and is chiral symmetry restored in the deconfined medium ? Is there another state (CGC) of matter at low x, what are its features, and how does it evolve into the QGP ? What is the structure and dynamics inside the proton (parton spin, L) and what do we learn from parity violation and polarization measurements ?

4. 4 The Measurement Pillars of R2D Particle Identified Jet measurements Measurement  -jets & flavor tagged jets Detailed onium measurements Forward (low x) physics Bulk observables in 4  High rate spin measurements

5. 5 Evolution of a strongly interacting system Measurements: Initial conditions (  HBT, low-x physics) Composition above T c (partons, di-quarks, pre-hadrons ?) Parton density (jet tomography, flavor, intra-, inter-jet correlations) Deconfinement T c (Quarkonium melting) Shuryak QM04 ?

6. 6 What are the initial conditions ? Color Glass Condensate (CGC): gluon saturation at low Q 2. Measure –Mid – forward rapidity correlations (hep-ph/0403271) –Direct photons at forward rapidities –  HBT (coherence of sea- quark source?) –Drell-Yan in forward region (hep-ph/040321) –R pA, R AA of heavy mesons in forward direction (hep- ph/0310358) requires tracking, calorimetry and PID over large  -range. ln (1/x)

7. 7 Bulk dynamics in 4  Bulk dynamics in 4  c hange ( , pT)  vary (  B,T)  vary x limiting fragmentation forward HBT increasing y Need tracking & PID forward

8. 8 In and out of a sQGP What are the degrees of freedom above T C ? Is chiral symmetry restored above T C ? How does hadronization and spontaneous breaking of chiral symmetry (SBCS) occur ? Shuryak QM04 ?

9. 9 The sQGP degrees of freedom and chiral symmetry restoration C.Greiner (Jamaica 04): multi-gluon interactions (e.g.strong 2 to 3) Recombination models: constituent quark (dressed up valence quarks) C.Greiner (SQM04): high mass resonances near T c (Hagedorn states) E.Shuryak (QM04): colored and colorless bound states above T c Measurements: High mass resonance shifts due to partonic bound states (Shuryak) Resonances to prove SBCS –Is off mass shell resonance (e.g. shifting or broadening in mass) visible in chiral partner pairs (  and a 1 ) or (  and  ) ? Resonances in jets –Is the leading particle resonance different from the bulk matter resonances (off shell vs on shell, same side vs away side, leading vs. next- to-leading)

10. 10 Hadronization and fragmentation via particle identified jet physics pTpT pQCD Hydro ~ 2 GeV/c~ 6 GeV/c Soft Medium modified fragmentation (jet quenching) 0 p T independence of pbar/p ratio. p/  and  /K ratio increases with p T to > 1 at p T ~ 3-4 GeV/c in central collisions. Suppression factors of p,  different to that of , K 0 s in the intermediate p T region. Parton recombination and coalescence Fragmentation ~ 30 GeV/c ? LHC, RHIC-II SPS, RHIC-I

11. 11  0 in pp: well described by NLO Ingredients (via KKP or Kretzer) –pQCD –Parton distribution functions –Fragmentation functions p+p->  0 + X Hard Scattering Thermally- shaped Soft Production hep-ex/0305013 S.S. Adler et al. “Well Calibrated”

12. 12 Strange particles in pp Specific NLO calculation describes K 0 reasonably well, but is off for  W.Vogelsang:  maybe  is too heavy, problems with heavy particles B.Jaffe (PAC meeting): maybe we need to look at fragmentation again RHIC-II will be the premier pp machine in the next decade because of its detector capabilities

13. 13 Do we understand fragmentation and its modification ? statistical approach based on measured inclusive cross sections of baryons in e+e- annihilation: alternate: de Florian et al., (1998) or J.J.Yang (2001,2002) Induced Gluon Radiation  ~collinear gluons in cone  “Softened” fragmentation Modification according to Gyulassy et al. (nucl-th/0302077) Quite generic (universal) but attributable to radiative rather than collisional energy loss 2 GeV baryon in a 10 GeV jet zz

14. 14 Yu.Dokshitzer Different partons lose different amounts of energy Examples: 1.) dead cone effect for heavy quarks: For heavy quarks in the vacuum and in the medium the radiation at small angles is suppressed (Dokshitzer & Kharzeev, PLB 519 (2001) 199) 2.) gluon vs. quark energy loss: Gluons should lose more energy and have higher particle multiplicities due to the color factor effect.

15. 15 Gluon jet selections at RHIC-II 1.) Large rapidity interval correlations (Mueller-Navelet Jets) 2.) Three jet events (?) 3.) P T -dependence of  -jets (?) low-x gluon 0.001< x g < 0.1 high-x valence quark 0.3 < x q < 0.7

16. 16 The goal of particle identified fragmentation in the medium 1.) we need to understand fragmentation (hadronization) in pp collisions 2.) use the medium modified fragmentation functions in AA collisions 3.) Different flavor contributions to D(z) at different z lose different  z in the opaque medium. Measure fragmentation functions in pp & modifications in AA. Study z = p hadron /p jet and x dependence : High p T identified particles Intra- and inter-jet particle correlations Large  acceptance for  -tagged jets Essential to understand hadronization 0.2 < z < 1  7 < p < 30 GeV/c 0.1 < x < 0.001  0 <  < 3 p q,g > 10 GeV/c all  10 6 particles in AA

17. 17  -charged hadron correlations in pp and AA 0-5% 10-30%5-10% 30-50%50-70% pp Quark vs. gluon jet ?, baryon-meson effect ? flavor conservation ? No significant difference for different trigger particle species at intermediate trigger pt. But we are statistics limited, we need  Anti-  K to higher pt Anticipated R2D rates: 50,000  pairs > 4 GeV/c, 5,000 pp pairs > 10 GeV/c STAR preliminary

18. 18 Asymmetry might develop as a function of trigger pt (increased ‘jettiness’) (Same side – away side) two particle correlation strength in central Au-Au Collisions at RHIC Strange trigger, charged associated particles (associated pt > 2 GeV/c) trigger pt (GeV/c) STAR preliminary STAR preliminary

19. 19 Requirements for a complete jet program Broadening in  and pT in pp (  +jet) and AA Full coverage in tracking and pid and calorimetry R2D rates per RHIC year: 40 GeV di-jets: 120k N Ch with pt>5 GeV/c in  -jets with E  = 20 GeV : 19,000 Need hadronic calorimetry in order to apply isolation cuts for  ’s Glueck et al., PRL 73, 388

20. 20 Onium physics – the complete program –Melting of quarkonium states (Deconfinement T C ) T diss (  ’) < T diss (  (3S)) < T diss (J/  )  T diss (  (2S)) < T diss (  (1S)) In order to resolve the question of melting of the states and its relevance to the sQGP we need to measure: the J/  production mechanism (octet vs. singlet model) the effect of thermal recombination the effect of nuclear absorption the effect of co-mover absorption the feed-down from  c all states

21. 21 Why a more complete onium program ? In pp: understand charm production (singlet vs octet model) In pA nuclear absorption: dependent on x F or x 2 ? In AA: co-mover absorption: Realistic cross sections ? E866 J/  data Quark shadowing and final state absorption + Gluon shadowing + Anti-shadowing + dE/dx A. Capella, D. Sousa, nucl-th/0303055

22. 22 Requirements for a complete onium program Full coverage high resolution forward calorimetry in order to measure not only the J/  but also the  c and the Y States Full coverage (|  |< 3) calorimetry and muon absorbers give us up to 1,000,000  c, 10,000 Y(2s) and 10,000 Y(3s) per RHIC year. The J/  alone is not sufficient ! R2D

23. 23 Charm flow by STAR/PHENIX STAR data very preliminary

24. 24 How can something so heavy flow with the light quarks ? Either lots of interactions of the heavy quark with the rest of the partonic phase or the hadronic phase (thermalization ?) What are the degrees of freedom ? : dressed up constituent quarks, bare heavy quarks, gluons, colorless bound states (glueballs ?). Let’s measure v 2 for D (through hadron channels), B-mesons (through J/  channels  J 

25. 25 RHIC-II: the premier pp machine for the next decade Attract new (and old) communities: RHIC Spin High energy hadron physics (Fermilab, Jlab, GSI) (proton driver at FNAL ?) - quark models, lattice gauge tests - meson/baryon exotica - glueballs, multiquark states - diffractive physics, multi-pomeron Contacts: M.Albrow, J.Appel (FNAL) E. Swanson (Pitt), T. Barnes (ORNL) Higher luminosity by varying quad position & superbunches

26. 26 Origin of Spin (of Proton) Gluons –  -jet (provides x range) * –Heavy quarks (D, B) * –Heavy quarkonia (J/  tag) –Large E T jets (E T ~ 40 - 50 GeV jets) Sea-quarks –Anti-quarks (W production) * –Strange quark (Charm-tagged W production) Orbital Angular Momentum? Polarization in AA? * part of original RHIC Spin program Transversity –Transversity dist. function of q and  q –Sivers effect (di-jets,  -jet)  S T  (P  k  )  0 –Quark mass dep. in QCD Lagrangian (B-jet) Beyond the Standard Model –New Interactions & chirality (parity violating hard-jet production) p p  ss c cc g W e D-jet

27. 27 RHIC-II: the premier pA machine for the next decade Attract new communities: (in preparation for EIC) eA community (Jlab, DESY) CGC theory -wee partons, CGC -high parton density QCD -gluon production, spin structure Contacts: A.Deshpande (SUNY) R.Milner (MIT), BNL- CGC folks

28. 28 Do we need RHIC-II in the LHC era ? Is the LHC viewing the sQGP through the distorted lens of the Color Glass Condensate ? (M. Gyulassy) Maybe the QGP degrees of freedom change from RHIC to LHC. Does the sQGP get weaker ? Are we in the sQGP sweet spot ? The case needs to be made strongly by the theory community that is interested in RHIC-II. The LHC detectors are not sufficient to characterize the sQGP.

29. 29 Requirements according to RHIC II Physics Pillars  Detailed properties of sQGP  Quarkonium: EMC/HCal Resolution, Acceptance, Rates  Jets: PID and tracking at high p T over full acceptance (  -jet, jet-jet)  Mechanisms of hadronization  PID at High p T, correlations, large  acceptance,  -tagged jets  Origin of Spin (of Proton)  Large  acceptance, jets,  -jet, high p T identified particles, correlations  Low x physics (CGC  QGP)  High-p T identified particle yields to large   Multi-particle correlations over small & large  range

30. 30 Do we need a new RHIC-II detector ? Understanding QCD at high density requires hermetic detectors with complete PID, HCal, EMCal, and tracking coverage. The upgrades to the existing RHIC detectors do not fulfill the necessary detector requirements. The LHC detectors do not cover all the requirements. A new device is required in order to harvest the uniqueness of the RHIC-II physics program.