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Quarkonia in Medium and their Fate at Future RHIC

Quarkonia in Medium and their Fate at Future RHIC. Ralf Rapp Cyclotron Institute + Physics Department Texas A&M University College Station, USA Workshop on “Future Perspectives in QCD at High Energy” Brookhaven National Laboratory, 19.07.06. Experiment:

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Quarkonia in Medium and their Fate at Future RHIC

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  1. Quarkonia in Medium and their Fate at Future RHIC Ralf Rapp Cyclotron Institute + Physics Department Texas A&M University College Station, USA Workshop on “Future Perspectives in QCD at High Energy” Brookhaven National Laboratory, 19.07.06

  2. Experiment: • no direct access (?) to spectral shape (unliker → e+e-): • J/y decay outside medium with1:200(r: 5:1) • number ofJ/y, Y’, Y, …and their pT-spectra, v2(pT) Challenges:- in-Medium -spectral functions - infer confinement of QGP! order parameter?! 1.) Introduction:Quarkonia Probing the QGP • immerse -pair into the QGP •  Vacuum properties change: • color screening (reduced binding) • dissociation reactions (and reverse!) • heavy-quark mass (→ mass and decay rates, threshold)

  3. Outline 1.) Introduction 2.) Medium Effects on Quarkonia 2.1 Color Screening 2.2 Dissociation Reactions 2.3 Heavy-Quark Masses in QGP 2.4 Spectral Functions and Correlators ↔ Lattice QCD 3.) Phenomenology in URHICs 3.1 Suppression and Regeneration 3.2The Role of Open Charm 3.3Observables 4.)Summary and Outlook

  4. 2.1 Onia in QGP: Color Screening and Binding • solve Schrödinger-Eq. with lattice-QCD U1(r) as potential [Shuryak etal ’04, Wong ’04, Alberico etal ’05, Mocsy etal ‘05, …] Charmonium Bottomonium • small binding energies aboveTc (~ screened Cornell pot.) • even smaller(!) for V1 = (1-a) U1 + a F1 [Wong ’06]

  5. (ii) “Quasifree” • Dissociation • neglects bound-state structure • appropriate for small binding • also involves (anti-) quarks [Grandchamp+RR ‘01] _ Dissociation Times 2.2.1 Charmonia in QGP: Dissociation Reactions • (i)Gluo- • Dissociation • sdiss(w)peaked atw ≈1.4eB • ok for free J/y (eBvac=640MeV) • not for screening, y’, cc [Bhanot+Peskin ‘84] Cross Sections

  6. 2.2.2 Bottomonium Lifetimes in QGP “Quasifree” Suppression Bottomonium Screening ~Tc [Karsch,Mehr +Satz ‘88] m~ gT [GeV] [Grandchamp etal ’05] • appreciable sensitivity to color screening! • significance at RHIC: tY ≈ 50 →5 fm/c

  7. 2.3 Heavy-Quark Masses in the QGP • quarkonium mass:my= 2mc* - eB • asymptotic energiesF∞ = U∞ - TS∞ U∞ [Kaczmarek +Zantow ‘05] F∞ • in-/decreasing heavy-quark mass ?! • close toTc: entropy contribution?

  8. - real part (pole ) ↔ screening, in-medium quark-mass - imaginary part (width) ↔ dissociation e.g. GY= ‹ npsdissvrel › ≈ 10fm-3 1mb ½ ≈ 100MeV (T≈250MeV) for tQGP=2fm/c: SY= exp[-GYtQGP] ≈ 0.37  “stable” J/y at RHIC unlikely • In-Medium Continuum: • Ethr(T) , nonperturbative Q-Q rescattering _ 2.4 Spectral Functions and Euclidean Correlators J/y s/w2 • Vacuum Spectral Function • ~ Bound State + Continuum: • sy(w) = Fy2 d(w-my) + w2Q(w-Ethr) fythr • In-Medium Bound-State / Resonance • sy (w) ~ Im Dy (w) : Y’ cont. w

  9. hc cc [Datta etal ‘04] • S-wave charmonia little changed to ~2Tc, P-wave signal enhanced(!) 2.4.2 Euclidean Correlation Functions (orR=G/Grecon) • accurate “data” from lattice QCD, integral over spectral function

  10. compatible with lattice • increase due to reduced Ethr(T)! • opposite trend as on lattice 2.4.3 Euclidean Correlator -- Potential Model • Spectral Function:sy(w,T) = Fy2 d(w-my) + w 2Q(w-Ethr) fythr • - Bound State: Schrödinger eq. with screened Cornell, or lQCD U1 • - Continuum: pQCD with Ethr(T) = 2mc+V∞ [Mocsy+Petreczky ‘05]

  11. - Q-QT-Matrix: • comprehensive treatment of • bound and scattering states • nonperturbative threshold • effects large • finite-width effects [Cabrera+RR in prep] 2.4.4 Eucl. Correlator -- Model II: T-Matrix Approach • use potential to solve • Lippmann-Schwinger-Eq. • for [Mannarelli+RR ’05, Cabrera+RR in prep] Correlator:

  12. cc [Datta etal ’04] • trends roughly as on lattice, except magn. + T-dep. of cc; threshold?! 2.4.4 Eucl. Correlators from T-Matrix Approach [Cabrera+RR in prep] • lattice U1-potential, mc=1.7GeV fix, Grecon(Ethr=2mD) hc

  13. 2.4.4 Eucl. Correlators from T-Matrix Approach [Cabrera+RR in prep] • lattice U1-potential, mc=1.7GeV fix, Grecon= G(T=1.1Tc) hc • sensitive to Grecon ! • ~ insensitive to width effects!

  14. 3.) Phenomenology in URHICs 3.1 Suppression + Regeneration 3.2 The Role of Open Charm 3.3 Observables

  15. - → ← J/y + g c + c + X key ingredients: reaction rate equilibrium limit (y -width) (links to lattice QCD) 3.1 Suppression and Regeneration in URHICs • 3-Stage Dissociation:nuclear (pre-eq) -- QGP -- HG • Stot = exp[-snucrL] exp[-GQGPtQGP ] exp[-GHGtHG ] • Regeneration in QGP + HG: • - microscopically: backward reaction (detailed balance!) - snuc(SPS) ≈ 4.5mb → used for RHIC predictions; - but: RHIC d-Au data → snuc≈1.5mb [PBM etal ’01, Gorenstein etal ’02,Thews etal ’01, Grandchamp+RR ’01, Ko etal ’02, Cassing etal ‘03] - for thermal c-quarks and gluons:

  16. e± Spectra J/y Coalescence at Tc [Greco etal ‘05] • yields differ • by factor 3 • importance • of Cronin • [Thews+ • Mangano’05] pQCD scatt. nonpert. scatt. [van Hees etal ‘05] [Ko etal ’02, Cassing etal ‘03 Gossiaux etal ’06, Zhang ’06, …] • need more detailed studies! (e.g. transport, Langevin) 3.2 The Role of Open Charm and Regeneration • softer c-quarks → more Y formation ↔ c-quark diffusion: tceq = mcT/D

  17. Update and Further Studies • snuc=1.5mb • sensitive to:c-quark diff., Tdiss • shape of RAAa problem?! • precise data! [X.Zhao+RR in prep] 3.3.1 Observables I: Centrality Dependence at RHIC → solve rate equation for expanding fireball (QGP-mix-hadron gas) Original Predictions [PHENIX ‘05] • snuc=4.4mb, tceq ~ 2.5fm/c (schem.) • QGP-regeneration dominant • sensitive to: mc* , (Ncc )2 [Grandchamp etal ’03]

  18. 3.3.2 Observables II: Excitation Function + Rapidity J/ySuppression vs. Regeneration SequentialY’+cc Suppression [Grandchamp +RR ’01] [Karsch,Kharzeev+Satz ‘06] • direct J/yessentially survive • (even at RHIC) • nontrivial “flat” dependence • similar interplay in rapidity!? • (need accurate dNc/dy)

  19. 3.3.3 Bottomonium at RHIC and LHC RHIC LHC • 50% feeddown from Y’, cb • importance of color-screening! • bottomonium suppression as unique QGP signature ?! [Grandchamp etal ’05]

  20. 5.) Summary • strong color-screening from lQCD heavy-quark potentials • short quarkonium lifetimes (tX=1-5 fm/c) • open-charm masses: open problem • Euclidean Correlation Functions: • - quantitative constraints on model spectral functions • - importance of nonperturbative threshold effects (T-matrix!) • - moderate sensitivity to width effects • Heavy-Ion Collisions: • - J/y above Tc : gain term! sensitive to c-quark diffusion, Tdiss • - flat excitation fct.: suppr. vs regeneration or (Y’, cc) only? • elliptic flow: v2(J/y) up to ~10% ?! • - Y suppression (very) sensitive to screening • - sQGP signature: Y more suppressed than J/y at RHIC+LHC !

  21. 2.4.4 Eucl. Correlators from T-Matrix Approach • lattice U1-potential, mc=1.8GeV fix, Grecon(Ethr=2mD) [Cabrera+RR in prep] hc cc • trends roughly agree with lattice, except T-dep. of cc – threshold?!

  22. Satz, Digal, Fortunato Rapp, Grandchamp, Brown Capella, Ferreiro • Percolation • Plasma • Comovers NA60 preliminary 3.5 Charmonium Observables at SPS Pb(158AGeV)-PbIn(158AGeV) –In • QGP-suppression prevalent • “jumps” / ”plateaus” in centrality? [Grandchamp etal ’03]

  23. 2.1 Onia in QGP: Color Screening and Binding Energies e.g. screened Cornell potential (linear+confining) [Karsch,Mehr+Satz ’88, Wong ’04, …] Charmonium Bottomonium ~Tc ~Tc m~ gT [GeV] m~ gT [GeV] • binding energies much reduced aboveTc • similar for lattice U1(r) , smaller(!) for F1

  24. 2.4.1 Langevin-Simul. at RHIC: Heavy-Quark RAA Resonances vs. pQCD Charm-pQCD (as,mD=1.5T) as , g 1 , 3.5 0.5 , 2.5 0.25,1.8 • hydro with Tc=165MeV, t ≈ 9fm/c • as and Debye mass independent • expanding fireball ≈ hydro • pQCD elastic scatt. moderate • resonance effects substantial [Moore and Teaney ’04] [van Hees,Greco+RR ’05]

  25. 3.4.3 Scrutinizing Charmonium Regeneration II: J/y Elliptic Flow Suppression only Thermal Coalescence at Tc [Greco etal ’04] [Wang+Yuan ’02] MB Au-Au • factor ~5 different! • transition inpt!?

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