1. Theory Highlights * of Quark Matter 2004 Ralf Rapp Texas A&M University Oakland, 17.01.04 * biased and incomplete, apologies for omissions

2. 1.Introduction: Exploring the Phase Diagram Bulk Properties: Equation of State Phase Transitions: (Pseudo-) Order Parameters Microscopic Properties: Spectral Functions

3. 2.) QCD Theory Color-Super-Conductor ; Chiral vs. Deconfinement Lattice: Critical Point, Charmonium 3.) QCD Bulk Properties at RHIC Color-Glass Condensate Opacity, Thermalization Quark Coalescence vs. Hydro HBT “Puzzle” 4.) Microscopic Probes of QCD Matter Resonance Spectroscopy E.M. Emission (Photons) Charm/onium 5.) Conclusions hot cool hot Outline

4. 2.1 Colorsuperconductivity and Compact Stars color+charge neutral u,d,s,e‾ matter  M s key parameter 2 4 gCFL CFL 2SC g2SC Normal M s 2 /(  M s -asym  1 d-s pair gapless Star Observables [Reddy] bulk: R≤8km favors quark EoS probes: - in-medium ν-propagation - grav. wave signal from binary mergers [Prakash] [Rajagopal]

5. 2.2 Confinement vs. Chiral Symmetry Breaking Order Parameters: Chiral Symmetry (m q →0): ‹qq› (quark condensate) Deconfinement (m q →∞): ‹L› (Polyakov loop) at C: m  →0 at D: m G →0 Mixing of  -Meson and 0 ++ Glueball connects ‹qq› and ‹L› [Fukushima] [Mocsy]: loop effects entangle ‹L› and ‹qq› D C Temperature T → Quark Mass m q → QCD

6. 2.3 QCD Lattice for GSI: The Critical Point T [MeV]  B [GeV] Quark Number Susceptibility at  q >0 [Karsch,Redlich,Ejiri]   B,c ≥ 400 MeV ([Fodor+Katz]: ~700MeV ) [Friman]

7. 2.4 QCD Lattice for RHIC: Charmonia [Karsch] RR suggests boundstates at T≤1.5T c reduced open-charm threshold? Spectral Functions J/ ,  c up to 2T c χ c dissolves close to T c [Asakawa,Datta] Singlet free energy: exp(-F 1 /T)= ‹ TrL r L 0 † › cc Potential from: F 1 =V 1 -TS - J/ 

8. 3.1 Initial: CGC 3.2 QGP : Opacity 3.3 QGP : Thermalization (nonpert?) 3.4 T c : Quark Coalescence vs. Hydro 3.5 T fo : HBT “Puzzle” 3.) QCD Bulk Properties at RHIC

9. 3.1 Pre-Equilibrium: Color Glass Condensate? Look forward in d-Au initial cond. in 3+1 hydro [Hirano,Nara] Qualitatively consistent with CGC [Jalilian-Marian,Venugopalan,Kovchegov] Note: valence-quark dominance (h + /h − >1)  same suppression? rapidity energy loss? Q s ~Q s0 exp(  s y)

10. GLV works quantitatively, incl. - d-Au (+away-side broad.) - re-app. in-plane away-side jet - connection to DIS [Vitev,Majumder,Salgado, Accardi,Barnaföldi,Povh]   ini  ≈ 20 GeV/fm 3 [Greiner] : absorpt. of colorless “prehadrons” ; problems: - v 2 of supp.+bulk, - SPS ?! 3.2 Opacity of QCD Matter: High-p t Frontier Notes: - non-jet baryon/meson for p T < 6 GeV - where does R AA rise again? LHC?!

11. 3.3 Thermalization and Nonperturbative QGP early thermalization Hydro v 0,1,2,4 Corrections: [Hirano,Heinz,Gavin] Resonant qq, qg, gg ↔ “meson” rescattering ?  Quasi-Quark “Boundstates”! above T c : Color-Coulomb +Instanton-Mol.  s (m D 2 )  0.5  [Shuryak,Zahed,Brown, Polchinski] [Asakawa+Hatsuda] T=1.4T c Lattice Spectr. Functs.

12. 3.4 Hydro vs. Coalescence: The 2-6GeV Regime v 2 : mass-dependent But: p/  (4GeV)≈0.3 [PHENIX]: 1±0.15 [Hirano,Nara] Challenges: p/  =1 + jet correlation,   elliptic flow [Fries,Hwa,Molnar]  universal partonic v 2 (p T /n) / n soft-soft ≈ thermal ( p T » m ) soft-hard: explicit thermal+jet (correlations!) [Greco et al.] [PHENIX] [STAR]

13. 3.5 HBT “Puzzle” Hydro/Transport models overpredict (R out ) 2 =D(x out,x out ) - 2D(x out,  t t) + D(  t t,  t t) [Kapusta,Wong]: incl. quant. phases in rescatt. ↔ initial size?! Multiphase Transport Model [Lin+Ko] positive R out - t correlation (not in Hydro, UrQMD …) Potential Remedies: [Teaney]: viscosity in hydro

14. 4.) Microscopic Probes of QCD Matter 4.1 Hadronic In-Medium Effects: Resonances and Chem. Freezeout 4.2 E.M. Emission 4.3 Charm/onium

15. 4.1 Resonance Spectroscopy at RHIC   ,    N,   ≈  5fm/c, T fo ≈110MeV, NN  -mass m  ≈const  -width   increases Model fit:  m  =-50MeV [Florkowski] But: Bose correlations, broadening, nonres. “background”, p-p ? Also: , f 0 /  factor ~2 too small  [STAR]

16. From Thermal to Chemical Freezeout at T c  175MeV : Chiral Restoration!  chiral partners must degenerate (m and  ): ,  a 1, N  N * (or:  L [Harada] )   Substantial medium modifications required (supported by CERES dileptons,   e + e - ) Challenge: Reconcile with chem. f.o. systematics !? (à la [Braun-Munzinger+Stachel etal],… ) Optimistic: measure (and calculate!) a 1  , N*(1535)  N 

17. 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 Π em (M,q) Im Π em (q 0 =q) e + e - γ e.m. correlator chemical off-equilibrium: QGP: q,g ≤ 1 HG:  ,K,.. > 0 [Niemi,Moore]

18. Direct Photons at SPS and RHIC large “pre-equilibrium” yield from parton cascade (no LPM) thermal yields ~ consistent QGP undersaturation small effect pQCD Cronin ~ π 0  T 0 ≈205MeV sufficient new WA98 points:  -Bremsstr. via soft  ? [Turbide etal]

19. [PHENIX] preliminary [PHENIX] preliminary 4.3 Charm I: Open Charm (Central A-A) (i) Yields RHIC: -30% for  =0  2: CGC [Tuchin], Color-Dipole [Raufeisen] LHC: CGC: N part ; nonlin. DGLAP: enhanced! [Kolhinen] (ii) p T -Spectra dE/dx : Null Effect?! [Djordjevic] v 2 (e ± ) : Thermalization?!

20. RHIC central: N cc ≈10-20, QCD lattice: J/  ’s to  ~2T c 4.3 Charm II: Charmonium Regeneration in QGP / at T c J/  + g c + c + X → ← [PBM etal, Thews etal] N part [Grandchamp] sensitivity to m c * - If c-quarks thermalize:

21. 5. Conclusions Produced Matter at RHIC is n Dense (opacity) n Thermalized (hydro) n probably nonperturbative (resonances,…) Microscopic probes required to assess the phase transition Need to find broad consensus on signatures to go beyond circumstantial evidence from the SPS