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Perspectives on RHIC-II: Heavy Ions and Hot+Dense Matter

Perspectives on RHIC-II: Heavy Ions and Hot+Dense Matter. Ralf Rapp Texas A&M University 1. RHIC-II Science Workshop BNL, 19.11.04. Introduction I: Hot and Dense QCD. + Thermal Field Theory. 2GeV<p<6GeV hadronization. non-pert QCD: p ~T equation of state. pQCD: p>>T energy loss.

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Perspectives on RHIC-II: Heavy Ions and Hot+Dense Matter

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  1. Perspectives on RHIC-II:Heavy Ions and Hot+Dense Matter Ralf Rapp Texas A&M University 1. RHIC-II Science Workshop BNL, 19.11.04

  2. Introduction I: Hot and Dense QCD + Thermal Field Theory 2GeV<p<6GeV hadronization non-pert QCD:p~T equation of state pQCD:p>>T energy loss medium probe(1) cluster(2-3) medium response (1000) e≈20GeVfm-3 quark scaling thermal, t0≈0.5fm/c mD≈0.7GeV nonabelian?! Mass/binding? phase transition? v2(pt,m) v2(pt/n) / n RAA(pt)

  3. - ‹qq› Genuine properties of QGP! Direct link to lattice QCD! [Bielefeld] cL cm [Tokyo] T=1.4Tc L 1.0 T/Tc Introduction II:Exploring the Phase Diagram • Thermalization at RHIC study: • chiral symmetry restoration • deconfinement • spectral properties of matter

  4. Outline 2.) Early Phases Matter Composition and Temperature 3.) QGP at p››T Nonabelian Effects Energy Deposition 4.) QGP at p~T Degrees of Freedom and Interactions Deconfinement 5.) Chiral Symmetry Restoration Order Parameters and Observables Medium Modifications of Hadrons 6.)Other Puzzles and Opportunities 7.)Concluding Remarks

  5. Electromagnetic Diagnostics: • photons and dileptons • gq→gq ~lg lq • qq→ee~ (lq )2 • thermal window: q0 , Mee≈ 1-3GeV • pre-equilibrium contribution?! 2.) Early Matter Composition • Initial State:CGC!? (fwd y)  • QGP (e=47cT4) or GP (e=16cT4) • qqproduction (CGC, sphalerons) • thermalization at t0≤ 0.5fm/c • initial temperature [Hirano+ Nara ‘04]

  6. 3.) Probing the QGP with high pt RAA(pt=6GeV) √s [GeV] 3.1 Energy Loss • Non-Abelian Charge [Wang ’04] DEg/DEq=9/4 + increasing gluon content with √s • Heavy Quarks • mQprovides extra scale • to disentangle, e.g., screening mass mD • Energy Gauge:high-pt photon tag; RAA(pt→∞)→1 ?! [Kharzeev+Dolshitzer, Djordjevic etal]] [Vitev ’04] • L2-Dependence Already observed in DIS on nuclei [HERMES] RHIC: medium expansion + centrality dependence L2

  7. Cone angle of shock front cosqemis = cs/c  qem=±(55º-63º) qemis [STAR] pT=(0.15-4)GeV 3.2 Energy Deposition and Correlations • Track “lost” energy: • thermalization? • correlations as advanced tests of coalescence[Hwa etal, Fries etal] • sonic shock wave in the hydrodynamic medium: [Shuryak]

  8. 4.) The Thermal Nature of QGP 4.1 Light-Quark Sector • (i) Perturbative QCD Rescattering • “anomalously” large widthG~g2T • gg↔ggg rescattering [Xu+Greiner ’04] • nonabelian plasma instabilites • [Moore etal ’04] Hydrodynamics requires early equilibration.How? Potential scenarios:(i)pQCD + ?! (ii)sQGP: heavy q, g + (many) boundstates (iii)q, g + (few) resonances large imaginary parts required(liquid:M~G vs. plasma:G<<T)

  9. Dilepton Radiation ratio to pert. qq rate _ Mee/mq (ii) Heavy Partons + Multiple Bound States → based on finite-T lattice potentials approach to “zero-binding line”  ~ stable-massr-resonance [Shuryak,Zahed, Brown, …] • thermal parton scattering through bound states? • composite interactions? quark scaling?

  10. (iii) “Hadronic” Resonances (few, colorless) • “moderately” heavy q+g, rescattering above threshold; • “hadron” formation above Tc → generalize coalescence • check with open heavy flavor Thermalization + “D”-Mesons Ellitpic Flow + Coalescence [van Hees+RR ’04] pQCD jet- quench [Djordjevic etal ’04] “D” _ [Müller etal ’95, Molnar’04] • dynamical origin of resonances? cc production? • onset of pQCD regime:pt>5-6GeV ? open bottom?

  11. 4.2 Quarkonia:Direct vs. Regeneration Centrality Dependence Rapidity Spectra - J/yExcitation Function → ← J/y + g c + c + X [Grandchamp etal] [Thews] * mc y • c-quark equilibration? • Deconfinement order parameter? Width?! QCD Lattice:J/y up to ~2Tc  in QGP Gy:inelastic reaction rate (width)

  12. (ii) Scrutinizing Charmonium Regeneration J/y Elliptic Flow Suppression only Thermal Coalescence at Tc [Greco etal ’04] [Wang+Yuan ’02] MB Au-Au Factor ~5 different! Transition inpt!? Furthermore:  Bottomonium suppression?!  Y’ (sensitive to in-medium D-mesons)

  13. at Tc: Chiral Restoration Low-Mass Dilepton Rate: r -meson dominated! ImPem ~ [ImDr+ImDw /10+ImDf /5] 5.) Chiral Symmetry Restoration - Order parameters: <qq> , fp , mq* ↔ Relation to observable? ~ “r - a1(1260)” (chiral partners) Axial-/Vector in Vacuum pQCD cont.

  14. Dilepton Emission Rates - - [qq→ee] [qq+O(as)] in-med HG ≈ in-med QGP ! Quark-Hadron Duality ?! 5.2 Vector Mesons at RHIC Hadronic Many-Body Theory • baryon effects important even at rB,net=0: • sensitive to rB,tot=rB+rB , most pronounced at low M • f more robust ↔ OZI -

  15. 5.3 Dileptons I: Lessons from SPS New Data (preliminary) 8% central pte >100MeV • enhancement concentrated at low (pair-) pt , theory low? • signal increases with ~ (Nch )2 • mass region between w and f

  16. 5.3 Dileptons II: RHIC [R. Averbeck, PHENIX] [RR ’01] QGP • low mass: thermal! (mostly in-medium r) • connection to Chiral Restoration: a1 (1260)→ pg ,3p • int. mass:QGP vs.cc → e+e-X,softeningdue to rescatt.?(v┴!) -

  17. mG→0 ms→0 D Quark Mass mq → pp • Theoretical Opportunities: • s ↔ 0++-glueball mixing, • connects‹qq›↔‹L› • interacting hadronic EoS:W (mB,T) • - chem. freezeout • - order parameter: QCD C [Fukushima] Temperature T → 5.4 Resonance Spectroscopy • Dilute matter, but versatile: • r-meson: Dmr=-50MeV • and/or broad. + thermal PS + BE ? • s→p+p -: threshold strength? (s↔p) • baryons! D++→p+p, N(1535)→Nh,… • reliable freezeout treatment (transport) [STAR] [Florkowski etal, Brown+Shuryak]

  18. 6.) (Some) Other Puzzles and Opportunities • constituent quark scaling accidental?[Molnar] • HBT: early QGP push + pos. x-t correlation?[Lin+Ko ‘02] • exotic particles: Q+[Nonaka etal ’04] ,Bc[Thews ‘99] , glueballs ? • global QGP polarization at finite b? [Wang ’04] • P, CP violation (UA(1) restoration)? [Kharzeev ’04] • …

  19. 7.) Summary • RHIC-IIunique (dedicated) facility to unravel • genuine (nonpert.) QCD properties of the QGP: • - nonabelian energy loss (high-pt) • - bound states / resonances (IM-dileptons, open charm) • - deconfinement (quarkonia; width?! J/y -regen, -supp) • - chiral symmetry restoration (LM-dileptons, resonances) •  mostly rare probes (incl. excitation functions) • importance of precision data + theory (redundancy) • to disentangle mechanisms very exciting opportunities ahead …

  20. e+ e- γ e.m. correlator 4.2 Direct Photons and Dileptons • Sources: • Initial hard scatt.: Drell-Yan / Compton (tag jets! [Gale]) • Pre-equilibrium: Radiation off jets [Gale] , • rescatt.+fragment. of secondaries (parton cascade [Bass]) • Thermal: Im Πem(M,q) Im Πem(q0=q) chemical off-equilibrium: QGP: lq,g≤ 1 HG: mp,K,..> 0 [Niemi,Moore]

  21. Direct Photons at SPS and RHIC [Turbide etal] • pQCD Cronin ~π0 • T0≈205MeV sufficient • new WA98 points: • pp-Bremsstr. via soft s ? • large “pre-equilibrium” yield • from parton cascade (no LPM) • thermal yields ~ consistent • QGP undersaturation small effect

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